Bread & wine
What it is
The substance of bread
The substance of wine
What the senses perceive
Color · taste · dimensions
The properties of bread & wine
The Aquinas series / 02
The Eucharist.
A change deeper
than sight.
The appearances of bread and wine remain. Christ truly gives us his body and blood. Follow St. Thomas Aquinas as he explores this mystery, one question at a time.
Explore the visual map SUMMA THEOLOGIAE · III, QUESTION 75REAL PRESENCEReceived in faith.
Explored with reason.Aquinas · article 1
Explored with reason.Aquinas · article 1
01 / The central distinction
What changes?
What remains?
Two terms help us read Aquinas’s map.
SubstanceWhat a thing is in its underlying reality. Here, “substance” is a philosophical term, not a list of chemical ingredients.
Accidents / appearancesA thing’s sensible properties, such as color, taste, and dimensions. “Accidents” here means properties, not mistakes.
CONSECRATIONBy God’s power
Christ’s body & blood
The whole substance changes
The substance of Christ’s body
The substance of his blood
The appearances remain
Color · taste · dimensions
The properties of bread & wine
The whole substance is converted; the appearances remain. This is a map of Aquinas’s distinctions, not a physical cross-section of the host.
02 / Follow the question
Eight articles.
One Eucharistic mystery.
A visual reading of Question 75. Each card summarizes Aquinas’s answer and links to the article itself.
Is Christ truly present?
Christ gives himself.
Christ’s wordFaith receives
Aquinas begins with Christ’s promise. His true body and blood are present in the sacrament. This presence is known through faith in God’s word; it expresses Christ’s love and draws us into union with him.
III, q. 75, a. 1Does the bread remain?
Its substance is changed.
Bread & wineBody & blood
After consecration, the substances of bread and wine no longer remain. Christ becomes present through their conversion into his body and blood. The familiar appearances continue.
III, q. 75, a. 2Is the bread annihilated?
It is converted.
What was breadChrist’s body
The bread is not reduced to nothing or dissolved into ingredients. Its substance is converted into Christ’s body. Conversion explains both the end of the bread’s substance and the real presence of Christ.
III, q. 75, a. 3What kind of change is this?
Transubstantiation.
Whole substanceWhole substance
God’s power changes the whole substance of bread into Christ’s body, and the whole substance of wine into his blood. This exceeds the power of natural causes: the Creator can act at the root of a thing’s being.
III, q. 75, a. 4What do the senses encounter?
The appearances remain.
Color · taste · sizeStill perceived
The sensible properties of bread and wine remain real. Aquinas calls these “accidents.” The senses truly encounter these properties; faith receives what Christ reveals about the substance present under them.
III, q. 75, a. 5Does the bread’s form remain?
The whole substance changes.
Matter + formWholly converted
Aquinas’s “substantial form” means the principle by which something is the kind of thing it is. It is not its outline or shape. Neither the bread’s matter nor its substantial form remains; its sensible properties do.
III, q. 75, a. 6Does the change happen gradually?
It is instantaneous.
ConsecrationPresence begins
Aquinas locates the change at the completion of the consecratory words. God’s action brings about the conversion at once. Christ does not become present by degrees, as though the host were partly changed along the way.
III, q. 75, a. 7How should we describe it?
“Converted into.”
Bread’s substanceChrist’s body
Aquinas carefully distinguishes conversion from making something out of a material that remains. “Made of bread” needs qualification: bread does not persist as material composing Christ’s body. The whole substance is converted.
III, q. 75, a. 803 / Room for questions
Stay with the mystery.
Aquinas’s distinctions invite careful questions. Open one to explore further.
If it still looks and tastes the same, are the senses mistaken?
Aquinas says the sensible properties really remain. Sight and taste encounter those properties accurately. Knowing who is present comes through faith in Christ’s word; it goes beyond what those senses can establish.
III, q. 75, a. 5 · reply to objection 2Does Christ leave heaven to become present on the altar?
Aquinas explains that Christ’s body becomes present through the conversion of the bread, rather than by traveling from heaven. His presence is sacramental: it is a real presence in a manner proper to this sacrament.
III, q. 75, a. 1 · reply to objection 3III, q. 75, a. 2When the host is broken, is Christ divided?
The Catechism teaches that Christ remains whole in every part of either species. The breaking affects the appearances; it does not divide the living Lord. His Eucharistic presence endures as long as the Eucharistic species remain.
Catechism 1377How does this differ from the Five Ways?
The Five Ways begin with creation and reason toward God. Here Aquinas begins with a truth received through revelation: Christ gives us his body and blood. Reason helps clarify what that teaching means, while the mystery itself is received in faith.
III, q. 75, a. 1Revisit the Five WaysFor Aquinas, this teaching leads toward communion.
Love desires
to be with the beloved.
In article 1, he connects the Eucharist with friendship: Christ unites us to himself through the truth of his body and blood. Understanding serves an encounter.
III, q. 75, a. 1