Today is the memorial of St. Thomas Aquinas. St. Thomas is known as the Angelic Doctor: he is a Doctor of the Church and he was blessed by God, through two angels, with pure chastity. He authored the great Eucharistic hymn Pange lingua. As my friend Tiber Jumper points out, one stanza of this chant succinctly captures the Church's perennial teaching on the transubstantiation of the bread and wine into the very Body, Blood, Soul, and Divinity of Jesus Christ:
Verbum caro, panem verum verbo carnem efficit:
fitque sanguis Christi merum, et si sensus deficit,
ad firmandum cor sincerum sola fides sufficit.
A rough translation of this is:
The Word-made-flesh (Verbum caro), true bread (panem verum) -- by His word (verbo) -- into flesh (carnem) turns (efficit), and makes (fitque) the Blood of Christ (sanguis Christi) of wine (merum); and if the senses fail (et si sensus deficit), to strengthen (ad firmandum) the pure heart (cor sincerum) faith alone (sola fides) suffices (sufficit).