Excerpti: The Homily, Part III: What is the purpose of the homily?

This is the third installment in the current Excerpti (extracts) series on the homily. This is Part III: What is the purpose of the homily?

Summary
First, here are two dynamite quotes:

• "The best catechesis on the Eucharist is the Eucharist itself well celebrated." (Synod of Bishops, XI Ordinary General Assembly, Propositiones, n. 19)
• "Given the importance of the word of God, the quality of homilies needs to be improved." (Pope Benedict XVI, Sacramentum Caritatis, n. 46)

There seems to be a common misconception that all the homily is, is an explanation of the Scripture that was read and an application of it to our lives. (Of course, there's an equally common misconception that a homily is where off-topic jokes are told and valuable football-watching time is wasted.) A homily is more than that. In addition to exposition on Scripture, the homily teaches the faithful about the truths and mysteries of the faith, about proper Christian behavior, and about the liturgy itself.

• The homily teaches and illustrates the truths and mysteries of the faith as well as the norms for Christian living, touching upon the whole of Christian teaching. (Cf. CIC, can. 386 §1, 528 §1, can. 767 §1; CCEO, can. 614 §1)
• The homily provides liturgical catechesis. (Cf. GIRM, n. 13)
• The homily explains the texts heard in the liturgy. (Cf. GIRM, nn. 29, 55, 65)
  
• The homily is based on Scripture, Tradition, and the Magisterium. (Cf. Divino Afflante Spiritu, n. 50; GIRM, n. 65; Redemptionis Sacramentum, n. 67)
• The homily should be relevant to the liturgical celebration of the day or season. (Cf. GIRM, n. 65)
• The quality of homilies must improve: they must not be generic or abstract, they must not dwell solely on the profane and political, and they must not use pseudo-religious material as sources. (Cf. Redemptionis Sacramentum, n. 67; Sacramentum Caritatis, n. 46)
  

Western Canon Law
"The diocesan Bishop is bound to teach and illustrate to the faithful the truths of faith which are to be believed and applied to behavior. ... He is also to ensure ... that the whole of Christian teaching is transmitted to all." (CIC, can. 386 §1)

"The parish priest ... is therefore to see to it that the lay members of Christ's faithful are instructed in the truths of faith, especially by means of the homily on Sundays and holydays of obligation and by catechetical formation." (CIC, can. 528 §1)

"In the course of the liturgical year, the mysteries of faith and the rules of Christian living are to be expounded in the homily from the sacred text." (CIC, can. 767 §1)

Eastern Canon Law
"The homily, in which during the course of the liturgical year the mysteries of faith and the norms of Christian living are expounded from Sacred Scripture, is strongly recommended as part of the liturgy itself." (CCEO, can. 614 §1)

Other Documents
"[T]he holy Synod charges pastors, and all who have the cure of souls, that they frequently, during the celebration of mass, expound either by themselves, or others, some portion of those things which are read at mass, and that, amongst the rest, they explain some mystery of this most holy sacrifice, especially on the Lord's days and festivals." (Council of Trent, 1562 - Session XXII, Chapter VIII)

"Let priests therefore ... assiduously distribute the heavenly treasures of the divine word by sermons, homilies and exhortations; let them confirm the Christian doctrine by sentences from the Sacred Books and illustrate it by outstanding examples from sacred history and in particular from the Gospel of Christ Our Lord; and - avoiding with the greatest care those purely arbitrary and far-fetched adaptations, which are not a use, but rather an abuse of the divine word - let them set forth all this with such eloquence, lucidity and clearness that the faithful may not only be moved and inflamed to reform their lives, but may also conceive in their hearts the greatest veneration for the Sacred Scripture." (Pope Pius XII, 1943 - Divino Afflante Spiritu, n. 50)

"... the homily or sermon in which the official head of the congregation recalls and explains the practical bearing of the commandments of the divine Master and the chief events of His life, combining instruction with appropriate exhortation and illustration of the benefit of all his listeners." (Pope Pius XII, 1947 - Mediator Dei, n. 21)

"For it is from scripture that lessons are read and explained in the homily[.]" (Second Vatican Council, 1963 - Sacrosanctum Concilium, n. 24)

"By means of the homily the mysteries of the faith and the guiding principles of the Christian life are expounded from the sacred text, during the course of the liturgical year[.]" (Second Vatican Council, 1963 - Sacrosanctum Concilium, n. 52)

"Within the cycle of a year, moreover, [Holy Mother Church] unfolds the whole mystery of Christ, from the incarnation and birth until the ascension, the day of Pentecost, and the expectation of blessed hope and of the coming of the Lord. Recalling thus the mysteries of redemption, the Church opens to the faithful the riches of her Lord's powers and merits, so that these are in some way made present for all time, and the faithful are enabled to lay hold upon them and become filled with saving grace." (Second Vatican Council, 1963 - Sacrosanctum Concilium, n. 102)

"A homily on the sacred text means an explanation, pertinent to the mystery celebrated and the special needs of the listeners, of some point in either the readings from sacred Scripture or in another text from the Ordinary or Proper of the day's Mass." (Sacred Congregation of Rites, 1964 - Inter Oecumenici, n. 54)

"Because the homily is part of the liturgy for the day, any syllabus proposed for preaching within the Mass during certain periods must keep intact the intimate connection with at least the principal seasons and feasts of the liturgical year, {Cf. Sacrosanctum Concilium, nn. 102-104} that is, with the mystery of redemption." (Sacred Congregation of Rites, 1964 - Inter Oecumenici, n. 55)

Regarding the celebration of marriage outside of Mass: "After the reading of the epistle and gospel from the Missa pro sponsis, there shall be a sermon or homily based on the sacred text. {Cf. Sacrosanctum Concilium, n. 52}" (Sacred Congregation of Rites, 1964 - Inter Oecumenici, n. 74/a)

"The people have the right to be nourished by the word of God proclaimed and explained. Accordingly priests are to give a homily whenever it is prescribed or seems advisable[.]" (Sacred Congregation of Rites, 1967 - Eucharisticum Mysterium, n. 20)

"The homily has as its purpose to explain to the faithful the word of God just proclaimed and to adapt it to the mentality of the times. The priest, therefore, is the homilist; the congregation is to refrain from comments, attempts at dialogue, or anything similar." (Sacred Congregation for Divine Worship, 1970 - Liturgicae Instaurationes, n. 2/a)

"[T]he homily ... explains the Word of God proclaimed in the liturgical assembly for the faithful there present, in a manner suited to their capacity and way of life, and relative to the circumstances of the celebration." (?, ???? - Eucharistiae Participationem, n. 15)

"The homily explaining the word of God should be given great prominence in all Masses with children." (Sacred Congregation for Divine Worship, 1973 - Directorium de missis cum pueris, n. 48)

"This remark is even more valid for the catechesis given in the setting of the liturgy, especially at the Eucharistic assembly. Respecting the specific nature and proper cadence of this setting, the homily takes up again the journey of faith put forward by catechesis, and brings it to its natural fulfillment. At the same time it encourages the Lord's disciples to begin anew each day their spiritual journey in truth, adoration and thanksgiving. Accordingly, one can say that catechetical teaching too finds its source and its fulfillment in the Eucharist, within the whole circle of the liturgical year. Preaching, centered upon the Bible texts, must then in its own way make it possible to familiarize the faithful with the whole of the mysteries of the faith and with the norms of Christian living. Much attention must be given to the homily: it should be neither too long nor too short; it should always be carefully prepared, rich in substance and adapted to the hearers, and reserved to ordained ministers." (Pope John Paul II, 1979 - Catechesi Tradendae, n. 48)

"The reading of Scripture cannot be replaced by the reading of other texts, however much they may be endowed with undoubted religious and moral values. ... Indeed the homily is supremely suitable for the use of such texts, provided that their content corresponds to the required conditions, since it is one of the tasks that belong to the nature of the homily to show the points of convergence between revealed divine wisdom and noble human thought seeking the truth by various paths." (Pope John Paul II, 1979 - Dominicae Cenae, n. 10)

"The purpose of the homily is to explain to the faithful the Word of God proclaimed in the readings, and to apply its message to the present." (Sacred Congregation for Sacraments and Divine Worship, 1980 - Inaestimabile Donum, n. 3)

"Christ is present in his word as proclaimed in the assembly and which, commented upon in the homily, is to be listened to in faith and assimilated in prayer." (Pope John Paul II, 1988 - Vicesimus quintus annus, n. 7)

"In the Catholic Eucharistic Liturgy, the homily which forms part of the liturgy itself is reserved to the priest or deacon, since it is the presentation of the mysteries of faith and the norms of Christian living in accordance with Catholic teaching and tradition. {Cf. CIC, can. 767 and CCEO, can. 614 §4}" (Directory on Ecumenism, n. 134)

"The homily, being an eminent form of preaching, qua per anni liturgici cursum ex textu sacro fidei mysteria et normae vitae christianae exponuntia, {Sacrosanctum Concilium, n. 52; cf. CIC, can. 767, §1} also forms part of the liturgy." (Congregation for the Doctrine of the Faith, 1997 - Ecclesiae de Mysterio, art. 3 §1)

"Indeed, since the use of the vernacular in the Sacred Liturgy may certainly be considered an important means for presenting more clearly the catechesis regarding the mystery that is inherent in the celebration itself, the Second Vatican Council also ordered that certain prescriptions of the Council of Trent that had not been followed everywhere be brought to fruition, such as the homily..." (GIRM, n. 13)

"Although in the readings from Sacred Scripture God’s word is addressed to all people of every era and is understandable to them, nevertheless, a fuller understanding and a greater effectiveness of the word is fostered by a living commentary on the word, that is, the homily, as part of the liturgical action. {Cf. Sacrosanctum Concilium, n. 52}" (GIRM, n. 29)

"[I]n the readings, as explained by the homily, God speaks to his people, opening up to them the mystery of redemption and salvation and offering them spiritual nourishment; and Christ himself is present in the midst of the faithful through his word." (GIRM, n. 55)

"The homily is ... necessary for the nurturing of the Christian life. It should be an exposition of some aspect of the readings from Sacred Scripture or of another text from the Ordinary or from the Proper of the Mass of the day and should take into account both the mystery being celebrated and the particular needs of the listeners. {Inter Oecumenici, n. 54}" (GIRM, n. 65)

"Particular care is to be taken so that the homily is firmly based upon the mysteries of salvation, expounding the mysteries of the Faith and the norms of Christian life from the biblical readings and liturgical texts throughout the course of the liturgical year and providing commentary on the texts of the Ordinary or the Proper of the Mass, or of some other rite of the Church. {Cf. Council of Trent, Session XXII, Chapter VIII; GIRM, n. 65} It is clear that all interpretations of Sacred Scripture are to be referred back to Christ Himself as the one upon whom the entire economy of salvation hinges, though this should be done in light of the specific context of the liturgical celebration. In the homily to be given, care is to be taken so that the light of Christ may shine upon life's events. Even so, this is to be done so as not to obscure the true and unadulterated word of God: for instance, treating only of politics or profane subjects, or drawing upon notions derived from contemporary pseudo-religious currents as a source." (Congregation for Divine Worship and the Discipline of the Sacraments, 2004 - Redemptionis Sacramentum, n. 67)

"The Council Fathers also urged the celebrant to treat the homily as part of the liturgy, aimed at explaining the word of God and drawing out its meaning for the Christian life. {Cf. Sacrosanctum Consilium, 52}" (Pope John Paul II, 2004 - Mane Nobiscum Domine, n. 13)

"The best catechesis on the Eucharist is the Eucharist itself well celebrated. Because of this ordained ministers are asked to consider the celebration as their main duty. In particular, they must prepare the homily with care, basing themselves on an appropriate knowledge of Sacred Scripture. The homily should put the Word of God, proclaimed in the celebration, in profound relationship with the sacramental celebration {cf. Sacrosanctum Concilium, n. 52} and with the life of the community, so that the Word of God is the foundation and life of the Church and is transformed in food by prayer and daily life. The homily molded by the teachings of the Fathers of the Church is a true mystagogy, that is, a true initiation to the mysteries celebrated and lived. In addition, the possibility was suggested of taking recourse – stemming from the triennial lectionary – to 'thematic' homilies that, in the course of the liturgical year, could address the great topics of the Christian faith: the Creed, the Our Father, the parts of the Mass, the Ten Commandments and other arguments. These thematic homilies should correspond to what has again been authoritatively proposed by the Magisterium of the Church in the four 'pillars' of the Catechism of the Catholic Church and in the recent Compendium. With this objective, the elaboration of pastoral material was proposed, based on the triennial lectionary, which puts the proclamation of the Scriptures in relationship with the doctrines of the faith that spring from the same." (Synod of Bishops, XI Ordinary General Assembly, 2005 - Propositiones, n. 19)

"Given the importance of the word of God, the quality of homilies needs to be improved. The homily is ... meant to foster a deeper understanding of the word of God, so that it can bear fruit in the lives of the faithful. Hence ordained ministers must 'prepare the homily carefully, based on an adequate knowledge of Sacred Scripture' {Propositio 19}. Generic and abstract homilies should be avoided. In particular, I ask these ministers to preach in such a way that the homily closely relates the proclamation of the word of God to the sacramental celebration {Cf. Sacrosanctum Concilium, n. 52} and the life of the community, so that the word of God truly becomes the Church's vital nourishment and support. The catechetical and paraenetic aim of the homily should not be forgotten. During the course of the liturgical year it is appropriate to offer the faithful, prudently and on the basis of the three-year lectionary, 'thematic' homilies treating the great themes of the Christian faith, on the basis of what has been authoritatively proposed by the Magisterium in the four 'pillars' of the Catechism of the Catholic Church and the recent Compendium, namely: the profession of faith, the celebration of the Christian mystery, life in Christ and Christian prayer. {Cf. Propositio 19}" (Pope Benedict XVI, 2007 - Sacramentum Caritatis, n. 46)

Excerpti: The Homily, Part II: When should there be a homily?

This is the second post in the Excerpti (extracts) series on the homily. This is Part II: When should there be a homily?

Summary
Apart from Canon Law, the main sources here are Sacramentum Concilium and Inter oecumenici.

• A homily is to be given on every Sunday and every holyday of obligation, and only a grave reason can justify its omission. This includes masses with children where they have their own Liturgy of the Word. (Cf. CIC, can. 528 §1, 767 §2; CCEO, can. 614 §2; Directorium de missis cum pueris, n. 17)
• A homily is strongly recommended during the week, especially during Advent and Lent, on a feast day or occasion of grief, and whenever there are a sufficient number of people present. (Cf. CIC, can. 767 §3)
• Every celebration of marriage must include a homily, even if the marriage is celebrated outside of Mass. (Cf. Inter Oecumenici, nn. 70, 74/a)
• Celebrations of baptism, penance, and funerals are fitting occasions for a homily as well. (Cf. Catechesi Tradendae, n. 48)
  

Western Canon Law
"The parish priest ... is therefore to see to it that the lay members of Christ's faithful are instructed in the truths of faith, especially by means of the homily on Sundays and holydays of obligation and by catechetical formation." (CIC, can. 528 §1)

"At all Masses on Sundays and holydays of obligation, celebrated with a congregation, there is to be a homily and, except for a grave reason, this may not be omitted." (CIC, can. 767 §2)

"It is strongly recommended that, if a sufficient number of people are present, there be a homily at weekday Masses also, especially during Advent and Lent, or on a feast day or an occasion of grief." (CIC, can. 767 §3)

Eastern Canon Law
"The homily ... is strongly recommended as part of the liturgy itself." (CCEO, can. 614 §1)

"Parish priests and rectors of churches have the obligation to take care that a homily is given at least during the Divine Liturgy on Sundays and feast days and that it is only omitted for a grave reason." (CCEO, can. 614 §2)

Other Documents
"[T]he holy Synod charges pastors, and all who have the cure of souls, that they frequently, during the celebration of mass, expound either by themselves, or others, some portion of those things which are read at mass, and that, amongst the rest, they explain some mystery of this most holy sacrifice, especially on the Lord's days and festivals." (Council of Trent, 1562 - Session XXII, Chapter VIII)

"Let priests therefore ... assiduously" -- that is, unceasingly -- "distribute the heavenly treasures of the divine word by sermons, homilies and exhortations[.]" (Pope Pius XII, 1943 - Divino Afflante Spiritu, n. 50)

"[T]he homily, therefore, is to be highly esteemed as part of the liturgy itself; in fact, at those Masses which are celebrated with the assistance of the people on Sundays and feasts of obligation, it should not be omitted except for a serious reason." (Second Vatican Council, 1963 - Sacrosanctum Concilium, n. 52)

"There shall be a homily on Sundays and holydays of obligation at all Masses celebrated with a congregation, including conventual, sung, or pontifical Masses. On days other than Sundays and holydays a homily is recommended, especially on some of the weekdays of Advent and Lent or on other occasions when the faithful come to church in large numbers." (Sacred Congregation of Rites, 1964 - Inter Oecumenici, n. 53)

"Unless there is some good, excusing reason, marriage shall be celebrated within Mass, after the gospel and homily. The homily is never to be omitted." (Sacred Congregation of Rites, 1964 - Inter Oecumenici, n. 70)

Regarding the celebration of marriage outside of Mass: "After the reading of the epistle and gospel from the Missa pro sponsis, there shall be a sermon or homily based on the sacred text. {Cf. Sacrosanctum Concilium, n. 52}" (Sacred Congregation of Rites, 1964 - Inter Oecumenici, n. 74/a)

"[P]riests are to give a homily whenever it is prescribed or seems advisable[.]" (Sacred Congregation of Rites, 1967 - Eucharisticum Mysterium, n. 20)

"On the Saturday evening, the Mass is to be celebrated as assigned in the calendar for Sunday and the homily ... [is] not to be omitted. (Sacred Congregation of Rites, 1967 - Eucharisticum Mysterium, n. 28)

"Sometimes ... it will be appropriate to celebrate the liturgy of the word, including a homily, with the children in a separate, but not too distant, room." (Sacred Congregation for Divine Worship, 1973 - Directorium de missis cum pueris, n. 17)

"The homily explaining the word of God should be given great prominence in all Masses with children." (Sacred Congregation for Divine Worship, 1973 - Directorium de missis cum pueris, n. 48)

"The homily should have its place not only in every Sunday and feast-day Eucharist, but also in the celebration of baptisms, penitential liturgies, marriages and funerals. This is one of the benefits of the liturgical renewal." (Pope John Paul II, 1979 - Catechesi Tradendae, n. 48)

Hear that? Homilies on a regular basis and even more frequently than that are "one of the benefits of the liturgical renewal". So don't skip the homily!

"There is to be a homily on Sundays and holy days of obligation at all Masses that are celebrated with the participation of a congregation; it may not be omitted without a serious reason. It is recommended on other days, especially on the weekdays of Advent, Lent, and the Easter Season, as well as on other festive days and occasions when the people come to church in greater numbers. {Cf. Inter Oecumenici, no. 53}" (GIRM, n. 66)

Excerpti: The Homily, Part I: Who can say the homily?

This is the first installment of a series I call Excerpti (extracts). Now that I have a collection of over 60 Church documents in digital form, I can search them easily, which means, if I want to know what they say about a particular term or concept, I can get that information (and its context) rather quickly. Most of the documents I cite are available in digital from on the Vox Ecclesiae page.

So this series will be a look at particular topics and what these documents say about them. I will provide the documents' excerpts in a chronological order (so that references to older documents refer to excerpts I've already provided), with the exception of Canon Law -- the Codex iuris canonici (CIC) for the Western Church, the Codex canonum ecclesiarum orientalium (CCEO) for the Eastern Churches -- which is presented first. Each excerpt is followed by its citation -- the author and year of publication, then the name of the document and the relevant section. I will start with a summary of what is to follow -- a bullet-point list of the conclusions arrived at.

For my first topic, I have chosen the homily. This is Part I: Who can say the homily?

Summary
The three primary sources for information on the minister of the homily are Canon Law, Ecclesiae de Mysterio, and Redemptionis Sacramentum. Ecclesia de Mysterio is referred to the most by the excerpts below; its subtitle is "On certain questions regarding the collaboration of the non-ordained faithful in the sacred ministry of the Priest".

• At the Eucharistic celebration of the Mass, the only people who can give a homily are a bishop, priest, or deacon, period. (Cf. CIC, can. 763-765, 767 §1)
• Those who have lost their clerical state or abandoned their sacred ministry may not give a homily. (Cf. Ecclesiae de Mysterio, art. 3 §5)
• No non-ordained member of the faithful can give a homily at a Mass, not even seminarians and theology students. (Cf. Ecclesiae de Mysterio, art. 3 §1)
• At a "Children's Liturgy", while a layperson can "speak to the children after the Gospel", this does not take the place of the homily, which must be given by an ordained minister. (Cf. Directorium de missis cum pueris, n. 24)
• A "dialogue homily" is envisioned only for Masses with Children. (Cf. Ecclesiae de Mysterio, art. 3 §3)
• In some circumstances, a layperson may preach in a church or oratory, but this requires express permission from the local ordinary; a priest or deacon can not give permission. Still, this preaching can not be a homily during a Mass. (Cf. CIC, can. 766; Redemptionis Sacramentum, n. 161)
• As regards preaching by laypeople, this is neither their right (as of a bishop) nor their faculty (as of a priest or deacon), but an exceptional permission. (Cf. CIC, can. 764-765; Ecclesiae de Mysterio, art. 2 §3)
• The permission given to laypeople to preach in particular situations is not to be regarded as "an ordinary occurrence nor as an authentic promotion of the laity". (Cf. Ecclesiae de Mysterio, art. 2 §4)
• It is preferable that testimonies from laypeople happen outside of the Mass; if they must happen during the Mass, then they are to be given after the Prayer after Communion. (Cf. Redemptionis Sacramentum, n. 74)

Two important sources not quoted below deserve mention. First is the Pontificial Commission for Legislative Text's authentic interpretation of can. 767 §1 which is that the "Diocesan bishop cannot dispense from the prescription that the homily is reserved to priests or deacons." (AAS, v. 79 (1987), p. 1249) In other words, a bishop cannot grant an indult to a layman to preach the homily. The second is the United States Conference of Catholic Bishops' norm on can. 766:

Preaching the Word of God is among the principal duties of those who have received the sacrament of orders (can. 762-764). The lay faithful can be called to cooperate in the exercise of the Ministry of the Word (can. 759). In accord with canon 766 the National Conference of Catholic Bishops hereby decrees that the lay faithful may be permitted to exercise this ministry in churches and oratories, with due regard for the following provisions:

If necessity requires it in certain circumstances or it seems useful in particular cases, the diocesan bishop can admit lay faithful to preach, to offer spiritual conferences or give instructions in churches, oratories or other sacred places within his diocese, when he judges it to be to the spiritual advantage of the faithful.

In order to assist the diocesan bishop in making an appropriate pastoral decision (Interdicasterial Instruction, Ecclesiae de Mysterio, Article 2 §3), the following circumstances and cases are illustrative: the absence or shortage of clergy, particular language requirements, or the demonstrated expertise or experience of the lay faithful concerned.

The lay faithful who are to be admitted to preach in a church or oratory must be orthodox in faith, and well-qualified, both by the witness of their lives as Christians and by a preparation for preaching appropriate to the circumstances.

The diocesan bishop will determine the appropriate situations in accord with canon 772 §1. In providing for preaching by the lay faithful the diocesan bishop may never dispense from the norm which reserves the homily to the sacred ministers (can. 767 §1; cf. Pontifical Commission for the Authentic Interpretation of the Code of Canon Law, 26 May 1987, in AAS 79 [1987], 1249). Preaching by the lay faithful may not take place within the Celebration of the Eucharist at the moment reserved for the homily.

Both are laws: the first (the Pontificial Commission's ruling) has universal force; the second (the USCCB's norm) has force within the US episcopal conference. (Thanks to Cameron from the Catholic Answers Forum for recommending these two sources. Cameron is a married deacon in the Catholic Church, and a canon lawyer!)

Western Canon Law
"Bishops have the right to preach the word of God everywhere, including in churches and oratories of religious institutes of pontifical right, unless the local bishop has expressly forbidden it in particular cases." (CIC, can. 763)

"Without prejudice to the prescript of can. 765, presbyters and deacons possess the faculty of preaching everywhere; this faculty is to be exercised with at least the presumed consent of the rector of the church, unless the competent ordinary has restricted or taken away the faculty or particular law requires express permission." (CIC, can. 764)

"Preaching to religious in their churches or oratories requires the permission of the superior competent according to the norm of the constitutions." (CIC, can. 765)

"Lay persons can be permitted to preach in a church or oratory, if necessity requires it in certain circumstances or it seems advantageous in particular cases, according to the prescripts of the conference of bishops and without prejudice to can. 767, §1." (CIC, can. 766)

"The most important form of preaching is the homily, which is part of the liturgy, and is reserved to a priest or deacon." (CIC, can. 767 §1)

Canon 766 says that lay persons can preach in a church, but canon 767 §1 explains that the homily, which is the "most important form of preaching" is the duty of a priest or deacon (or a bishop), that is, a man who has received Catholic ordination. Therefore, the permission for lay people to preach is restricted: they cannot give homilies. The "without prejudice to" part of can. 766 means that can. 766 "is non-operative when it comes to the matter specified in can. 767 §1" (Jimmy Akin). Thus, there are situations when a lay person can preach in a Church, but it can never be as or in place of a homily; they can preach at retreats, missions, etc.

Eastern Canon Law
"A pastor cannot habitually hand over to another his obligation of preaching to the people committed to his pastoral care except for a just reason approved by the local hierarch." (CCEO, can. 614 §3)

"The homily is reserved to a priest or, according to norm of particular law, also to a deacon." (CCEO, can. 614 §4)

Other Documents
"Let priests therefore ... assiduously distribute the heavenly treasures of the divine word by sermons, homilies and exhortations[.]" (Pope Pius XII, 1943 - Divino Afflante Spiritu, n. 50)

"... the homily or sermon in which the official head of the congregation recalls and explains..." (Pope Pius XII, 1947 - Mediator Dei, n. 21)

"This is the object not only of readings, homilies and other sermons given by priests..." (Pope Pius XII, 1947 - Mediator Dei, n. 101)

"Accordingly priests are to give a homily whenever it is prescribed or seems advisable[.]" (Sacred Congregation of Rites, 1967 - Eucharisticum Mysterium, n. 20)

"The priest, therefore, is the homilist[.]" (Sacred Congregation for Divine Worship, 1970 - Liturgicae Instaurationes, n. 2/a)

"With the consent of the pastor or rector of the church, one of the adults may speak to the children after the gospel, especially if the priest finds it difficult to adapt himself to the mentality of children." (Sacred Congregation for Divine Worship, 1973 - Directorium de missis cum pueris, n. 24)

The Latin for "may speak to the children after the gospel" is "post Evangelium verba ad pueros dirigat": literally, "direct words to the children after the Gospel". This is not the homily, and as such, must not take the place of the homily. The Latin would have used "homilia" to denote the giving of a homily, by a non-ordained adult, to the children. In other words, the children are not to be deprived of a homily, which can only lawfully be given to them by an ordained minister. (cf. What Have We Done to Our Children?, Adoremus Bulletin, Vol. IX, No. 10)

"Sometimes the homily intended for children should become a dialogue with them, unless it is preferred that they should listen in silence." (Sacred Congregation for Divine Worship, 1973 - Directorium de missis cum pueris, n. 48)

"Much attention must be given to the homily: it should be ... reserved to ordained ministers." (Pope John Paul II, 1979 - Catechesi Tradendae, n. 48)

"But these encouraging and positive aspects cannot suppress concern at the varied and frequent abuses being reported from different parts of the Catholic world: the confusion of roles, especially regarding the priestly ministry and the role of the laity (indiscriminate shared recitation of the Eucharistic Prayer, homilies given by lay people, lay people distributing Communion while the priests refrain from doing so)..." (Sacred Congregation for Sacraments and Divine Worship, 1980 - Inaestimabile Donum, Foreword)

"Accordingly the homily is to be given by the priest or the deacon. {Cf. Liturgicae Instaurationes, n. 2/a}" (Sacred Congregation for Sacraments and Divine Worship, 1980 - Inaestimabile Donum, n. 3)

"In the Catholic Eucharistic Liturgy, the homily which forms part of the liturgy itself is reserved to the priest or deacon, since it is the presentation of the mysteries of faith and the norms of Christian living in accordance with Catholic teaching and tradition. {Cf. CIC, can. 767 and CCEO, can. 614 §4}" (Directory on Ecumenism, n. 134)

"Canon 766 of the Codex Iuris Canonici establishes the conditions under which competent authority may admit the non-ordained faithful to preach in ecclesia vel oratorio. The use of the expression admitti possunt makes clear that in no instance is this a right such as that which is specific and proper to the Bishop {Cf. CIC, can. 763} or a faculty such as enjoyed by priests and deacons. {Cf. CIC, can. 764} The terms in which these conditions are expressed - 'If in certain circumstances it is necessary..., ...if in particular cases it would be useful...' in canon 766 - make clear the exceptional nature of such cases as well as the fact that such must always be done iuxta Episcoporum conferentiae praescripta. (Congregation for the Doctrine of the Faith, 1997 - Ecclesiae de Mysterio, art. 2 §3)

"In some areas, circumstances can arise in which a shortage of sacred ministers and permanent, objectively verifiable, situations of need or advantage exist that would recommend the admission of the non-ordained faithful to preaching. Preaching in churches or oratories by the non-ordained faithful can be permitted only as a supply for sacred ministers or for those particular reasons foreseen by the universal law of the Church or by Conferences of Bishops. It cannot, however, be regarded as an ordinary occurrence nor as an authentic promotion of the laity." (Congregation for the Doctrine of the Faith, 1997 - Ecclesiae de Mysterio, art. 2 §4)

"The homily, therefore, during the celebration of the Holy Eucharist, must be reserved to the sacred minister, Priest or Deacon {Cf. Catechesi tradendae, n. 48; [GIRM (1970), nn. 41, 42, 165;] Liturgicae instaurationes n. 2a; Inaestimabile donum, n. 3} to the exclusion of the non-ordained faithful, even if these should have responsibilities as "pastoral assistants" or catechists in whatever type of community or group. ... For the same reason, the practice, on some occasions, of entrusting the preaching of the homily to seminarians or theology students who are not clerics is not permitted." (Congregation for the Doctrine of the Faith, 1997 - Ecclesiae de Mysterio, art. 3 §1)

"A form of instruction designed to promote a greater understanding of the liturgy, including personal testimonies, or the celebration of eucharistic liturgies on special occasions (e.g. day of the Seminary, day of the sick etc.) is lawful, of in harmony with liturgical norms, should such be considered objectively opportune as a means of explicating the regular homily preached by the celebrant priest. Nonetheless, these testimonies or explanations may not be such so as to assume a character which could be confused with the homily." (Congregation for the Doctrine of the Faith, 1997 - Ecclesiae de Mysterio, art. 3 §2)

"As an expositional aide and providing it does not delegate the duty of preaching to others, the celebrant minister may make prudent use of 'dialogue' in the homily, in accord with the liturgical norms. {Cf. Directorium de missis cum pueris, n. 48}" (Congregation for the Doctrine of the Faith, 1997 - Ecclesiae de Mysterio, art. 3 §3)

Note that the reference is to the Directory for Masses with Children: that is when dialogue homilies may be used.

"Homilies in non-eucharistic liturgies may be preached by the non-ordained faithful only when expressly permitted by law and when its prescriptions for doing so are observed." (Congregation for the Doctrine of the Faith, 1997 - Ecclesiae de Mysterio, art. 3 §4)

"In no instance may the homily be entrusted to priests or deacons who have lost the clerical state or who have abandoned the sacred ministry." (Congregation for the Doctrine of the Faith, 1997 - Ecclesiae de Mysterio, art. 3 §5)

"The Homily should ordinarily be given by the priest celebrant himself. He may entrust it to a concelebrating priest or occasionally, according to circumstances, to the deacon, but never to a lay person. {Cf. CIC, can. 767 §1; Ecclesiae de mysterio, art. 3} In particular cases and for a just cause, the homily may even be given by a Bishop or a priest who is present at the celebration but cannot concelebrate." (GIRM, n. 66)

"The homily ... 'should ordinarily be given by the Priest celebrant himself. He may entrust it to a concelebrating Priest or occasionally, according to circumstances, to a Deacon, but never to a layperson. {Cf. GIRM, n. 66; cf. CIC, 767 §1; Ecclesiae de mysterio, art. 3 §1} In particular cases and for a just cause, the homily may even be given by a Bishop or a Priest who is present at the celebration but cannot concelebrate'. {GIRM, n. 66; cf. CIC, can 767 §1}" (Congregation for Divine Worship and the Discipline of the Sacraments, 2004 - Redemptionis Sacramentum, n. 64)

"It should be borne in mind that any previous norm that may have admitted non-ordained faithful to give the homily during the Eucharistic celebration is to be considered abrogated by the norm of canon 767 §1. {Cf. Ecclesiae de mysterio, art. 3 §1} This practice is reprobated, so that it cannot be permitted to attain the force of custom." (Congregation for Divine Worship and the Discipline of the Sacraments, 2004 - Redemptionis Sacramentum, n. 65)

"The prohibition of the admission of laypersons to preach within the Mass applies also to seminarians, students of theological disciplines, and those who have assumed the function of those known as 'pastoral assistants'; nor is there to be any exception for any other kind of layperson, or group, or community, or association. {Cf. Ecclesiae de mysterio, art. 3 §1}" (Congregation for Divine Worship and the Discipline of the Sacraments, 2004 - Redemptionis Sacramentum, n. 66)

"If the need arises for the gathered faithful to be given instruction or testimony by a layperson in a Church concerning the Christian life, it is altogether preferable that this be done outside Mass. Nevertheless, for serious reasons it is permissible that this type of instruction or testimony be given after the Priest has proclaimed the Prayer after Communion. This should not become a regular practice, however. Furthermore, these instructions and testimony should not be of such a nature that they could be confused with the homily, {Cf. Ecclesiae de mysterio, art. 3 §2} nor is it permissible to dispense with the homily on their account." (Congregation for Divine Worship and the Discipline of the Sacraments, 2004 - Redemptionis Sacramentum, n. 74)

"[T]he homily ... is reserved to the Priest or Deacon during Mass. As regards other forms of preaching, if necessity demands it in particular circumstances, or if usefulness suggests it in special cases, lay members of Christ’s faithful may be allowed to preach in a church or in an oratory outside Mass in accordance with the norm of law. {Cf. CIC, can. 766} This may be done only on account of a scarcity of sacred ministers in certain places, in order to meet the need, and it may not be transformed from an exceptional measure into an ordinary practice, nor may it be understood as an authentic form of the advancement of the laity. {Cf. Ecclesiae de mysterio, art. 2 §§3-4} All must remember besides that the faculty for giving such permission belongs to the local Ordinary, and this as regards individual instances; this permission is not the competence of anyone else, even if they are Priests or Deacons." (Congregation for Divine Worship and the Discipline of the Sacraments, 2004 - Redemptionis Sacramentum, n. 161)

"[O]rdained ministers are asked to consider the celebration as their main duty. In particular, they must prepare the homily with care, basing themselves on an appropriate knowledge of Sacred Scripture." (Synod of Bishops, XI Ordinary General Assembly, 2005 - Propositiones, n. 19)

"[O]rdained ministers must 'prepare the homily carefully, based on an adequate knowledge of Sacred Scripture'. {Propositio 19} ... In particular, I ask these ministers to preach in such a way..." (Pope Benedict XVI, 2007 - Sacramentum Caritatis, n. 46)