Modern understanding of Transubstantiation?

Has the church ever undertaken a more modern description of what transubstantiaion is? I’ve heard descriptions of it that relied on a philosophical description of matter (accidentals, substance, etc.) that reflected Aristotle’s understanding of the physical world. But now that we have a more complete understanding of what the world is made of, has anyone come up with a description that doesn’t rely on a 2300+ year old understanding of the physical world?

Hi JT,

The philosophical concepts that have been used to “explain” the eucharist are not dependent on a particular view of the world. Substance and accident are concepts that relate to all beings, substance being that without which a thing would not be what it is and accident being a characteristic that is not part of the substance. These concepts apply, no matter what you think of the composition of matter or what is your view of the universe. The Church holds that the substance of the bread and wine is replaced by the substance of Jesus Christ, body and soul, humanity and divinity.

Thomistic philosophy, based on that of Aristotle has sort of been “canonized” by the Church as being the philosophy that best explains and supports the spiritual realities of our religion. However there could be other philosophical systems that might give their own “explanation” of the mysteries such as the eucharist. However, one must remember above all that the Eucharist is a miracle and can never be explained “naturally”.

What do you think ?


Central to this teaching is that it is a mystery. As previously said, it can not be explained “naturally”. I find it best to simply think of it in the manner that I explain it to my children. "It looks like bread, feels like bread, and tastes like bread, but it’s NOT bread…it is the Body of Christ.

Just like the manna in the desert, it is a gift from God and even the faith to believe is likewise a gift from God. God freely offers this gift to all…we simply need to ask and to receive.

God Bless,

The encyclical Mysterium Fidei (see here) rejected such efforts, including the theories of transsignification and transfinalization.

It doesn’t follow that because Aristotle’s physics have been overtaken that his metaphysics are somehow obsolete. His metaphysics are not, in any way, dependent on his physics.

If you find the philosophical terms difficult, you can think of it as the appearances staying the same while what the Eucharist really is changing entirely.

:thumbsup: All Christians who believe in the Real Presence would agree with your statement, regardless of whether they subscribe to Transubstantiation, Sacramental Union or another understanding.

Mother and Father taught me that in a Catholic Mass the bread and wine indeed become the Body and Blood of Christ.
In a Catholic grade school we children learned that in a Catholic Mass the bread and wine DO become the Body and Blood of Christ.
What a beautiful teaching!!!


As one or two others have said, the Church’s definition does not depend on any particular understanding of the physical world. As far as it relies on any other branch of knowledge, it uses ( but is not dependet on ) the metaphysical explanation given by Thomas Aquinas ( you can study this in his Commentary on Aristotle’s Metaphysics, which you can find here: It would be best to begin with Book lV.

In a nut shell, a Substance is any thing which has a nature or essence that has an actual existence. Physical substances are essences ( or natures ) which exist in a particular matter ( the " matter " of a horse or a man or a chunck of coal for example).

But you cannot see this substance. It has matter informed by a specific form ( horse, man, coal, etc.). And all the properties, powers, etc. associated with this substance is what you see and measure, sense, etc. Aristotle and Thomas both call these accidents because they are essential and they exist in the Substance.
They do not exist without the substance.

What the Church says is that this substance is changed completely into the body and blood of Christ. But all the accidents remain, but they remain all alone, they no longer have a substance in which they inhere. There are two miricals here. First the substances of the bread and wine are changed into the Body and Blood of Christ. Secondly, the accidents of bread and wine remain, but in no substance or subject. The latter is a miracle because it is the only instance in which accidents exist, but in no subject.

The Catechism of the Catholic Church explains the basic truth but does not go into such detail.

I should add that both Aristotle and Thomas spoke of First Substance and Second Substance. I always get them mixed up, but one refers to the Substance mentioned above, which cannot be seen or measued and the other to the individual thing that you can actually touch, measure, etc. ( ).

But in Transubstantion, the whole substance ( first and second ) of the bread and wine ( first and second substance both, but without the accdents ) are changed into the whole substance of Christ ( both his first and second substances ), including all of his accidents, size, limbs, hair, human soul with all its attributes, and his Divinity as well. Thomas explainsi in the S.T. ( under the Real Presence ) that this is done, " according to the manner of the Sacrament. " You have to remember that we are speaking of Christ’s glorified body which is not limited or constrained by earthy limitations such as space and time. I don’t pretend to understand how this happens, but we believe that it is so.

I’m pretty sure the Church will never address this Definition again except by way of Chatechesis.


My problem with the philosophical description is that only gives a philosophical change. So if the Eucharist “becomes” something other than just bread, it seems that only a philosophical change is happening, not a physical change. “Substance” as defined by Aristotle only really addresses the philosophical interpretation of what something is.

We know the bread is made of atoms, arranged in a certain way by the growth of the wheat and the processing of the kernels of wheat into flour and then into bread. These atoms are the physical existence of the bread. The color and appearance of the bread comes from which waveforms of light bounce off of these atoms. The taste of the bread comes from how these atoms interact with the atoms in the cels of your tongue. So “accidents” derive from the actual physical substance of the thing in question.

When bread is blessed to become Eucharist, these atoms do not change. The accidents still come from the way that light bounces off the atoms, or the atoms chemically react to your tongue or digestive system. The physical substance of the bread does not change, nor do any of its physical properties. No changes occur that can be detected in the physical world.

The only difference is in properties that humans apply to classify the bread. To the physical world, saying “this bread was used in a Eurcharist ceremony” and “this bread once sat on that table” hold the same level of distinction. Without knowledge of the history of the bread, it couldn’t be classified.

If a change happened on some other plane of existence, and things on that plane of existence could affect our physical world, then the affect could be reliably and reproducibly detected. Simply writing it off as a “mystery” doesn’t seem any different than stating “I don’t know”. At that point, you could claim anything is a mystery.

I think that one day physics will be able to show how transubstantiation is possible with an equation on a blackboard.

Its not a merely a “philosophical” or nominal change, its a metaphysical/ontological change.

I hope you’re not conflating the term “substance” in regards to Aristotelian philosophy?

Again, this assumes nominalism. “Humans” are not “classifying” anything.

If by “the physical world” you mean “me” then you’re begging the question.

You got it backwards. The only “change” which “happens” occurs on this “plane of existence.”

What(or Whom) affects the metaphysical change in the elements is eternal and the effects of the miracle enacted through the words of consecration are veiled behind the accidents of the bread and wine. The ontological substance is changed with a change in the accidents.

The mystery is how it is done. That it is done and why has been revealed by a Source who by definition cannot lie.

The idea that all effects could be or ought to be “reliably and reproducibly detected” to be true begs the question. There are many things we know to be true that are not “reliably and reproducibly detected”.

Metaphysical and ontological changes are philosophical changes, since they are philosophical fields. The change is one of classification, not of change in the physical makeup of the bread, nor of any physical or observable properties of the bread.

My appologies. By “physical substance” I mean the matter which makes up the bread, as opposed to “substance” in Aristotelian philosophy which refers to the way in which an object is perceived and the role it is assumed to have.

I don’t follow. Humans are applying abstract descriptors to an object, and thus classifying it by default. “This bread was on that table” is applying the abstract concept of “things that have historically been on that table before” to the bread. The physical makeup of the object and its physical properties do not change, but humans have assigned an abstract descriptor to the object.

By the physical world I am talking about the physical reality in which we exist as a collection of atoms arranged in space. Solipsism does not apply here. Perhaps I can rephrase from “To the physical world” to “For all methods of detection and measurement in the physical world in which we exist”.

How is this change measured or detected? The only change is one of abstract classification.

Do you mean “without a change in the accidents” because I thought the claim is that the substance changes but the accidents do not?

So it all comes down to “because the Church says so”. No explanation outside of a philosophical one can be given then.

In an attempt to better clarify the ontological/metaphysical change that transubstantiation defines, Is there any other example of the Aristotelian substance of something changing while its accidentals remain the same? Is the Eucharist the only example of this? Are there any philisophical examples of physical objects that are not of a religious nature?

I agree with some of this, so would Thomas and the Church. The explanation given does not explain how the miracle is done, that is a miracle. Miracles, by definition, cannot be explained by science. The " philosophical " explaination explains what happens, not how.

The point I disagree with is that you define the philosophical explaination as some how not real, compared what science would say. The philosophical explaination is real, it is from the nature or essence of second substance ( unseen, underlying reality explained above ), that all the observable, measureable properties flow. Philosophy and science look at reality at two different levels. Generally, the professional atheist ( those who blog, chat, write, lecture, about atheism ), present themselves as spokesmen for science. But they do not speak for science because there are many scientists who are not atheists and even some who are also philosophers. There are even some atheist philosophers. And it was Aristotle, a pagan, who first laid out the argument that philosophy was a valid science since it dealt with what was most important about reality, the ultimate causes and nature of what exists. Yet he also defended the reality and value of mathematics and science. But he explained that the two sciences dealt with reality at two different levels, each valid and real.

Your claim that only science explains reality cannot be maintained logically.


The Book of Wisdom explains transubstantiation.

Instead of these things thou didst give thy
people food of angels,
and without their toil thou didst supply them
from heaven with bread ready to eat,
providing every pleasure and suited to every taste
For thy sustenance manifested thy sweetness
toward thy children;
and the bread, ministering to the desire of
the one who took it,
was changed to suit every one’s liking.
(Wisdom 16:20-21)

This is how the Book of Wisdom ends…

For the elements changed places with one another,
as on a harp the notes vary the nature of the rhythm,
while each note remains the same.
This may be clearly inferred from the sight of what took place.
For land animals were transformed into water creatures,
and creatures that swim moved over to the land.
Fire even in water retained its normal power,
and water forgot its fire-quenching nature.
Flames, on the contrary, failed to consume
the flesh of perishable creatures that walked among them,
nor did they melt the crystalline, easily melted
kind of heavenly food.
For in everything, O Lord, thou hast exalted
and glorified thy people;
and thou hast not neglected to help them at
all times and in all places.
(Wisdom 19:18-22)

That’s enough of an explanation for me.


There are some things that will always be beyond our understanding.

Characterizing the body and blood, soul and divinity of God with a math equation? Really?


It might be helpful to understand that the human soul, a spiritual substance, is the director of the organization of matter into what is known as a human being.

Thus if soul is affixed to matter, that matter, perforce, is a living body.

And since Christ’s soul, after the consecration of the bread, is affixed to the matter of the bread, it is a human being.

However, since Christ is also God, the flesh and blood of that human being, in the matter of that which was formerly bread, is glorified, and has properties beyond that which we are acquainted with in an ordinary person.

And that is why Christ is the bread you see in the Eucharist, because that is the form He wished to present Himself to us in.


This is not correct.

The the soul of Jesus is not affixed to the matter of the bread. The bread is gone. The bread ceases to exist. It only appears to be bread. There is nothing for Christ’s soul to affix to. It has become completely Jesus. It is the Lord.

The Eucharist is not a human being. If the Eucharist were a human being then we would see a 165lb man with arms and legs. The Eucharist is not a living body. The Eucharist is the real presence of Christ - it is the entire substance of Christ’s body, blood, soul and divinity. It is not his physical presence of the human person but the real presence of the substance of Jesus’ body, blood, soul and divinity.

You will never hear a theologian refer to the physical presence of Christ but only the real presence. You will never hear of a theologian refer to actual flesh or a physical body or a human person. There have been miracles where flesh has appeared, but these are not the norm.

The Eucharist which Christ left us is not his physical body but his real presence in the substance of himself. It is a subtle distinction.


The first Eucharist, when Jesus was with His apostles, he hadn’t died yet, so it couldn’t have been his glorified body, at least not then.

“Transubstantiation” occurs all the time – every time you eat.
Eg. nutrition: Eat beans; the substance of beans is changed into the substance of your human flesh. Transubstantiation. Inanimate material is consumed and converted into living flesh.

The difference between the Eucharist and ordinary nutrition has to do with the accidents. In eating beans, the accidents of beans no longer remain after being after the substance is converted into human flesh.
In the Eucharist, the accidents of bread remain, but they no longer adhere in any substance –
*not in the substance of bread (which is no longer there because it has been converted into the substance of Our Lord’s body and blood;
*and not the substance of Our Lord’s body, blood, soul and divinity.
CCC 1374-1377

After consecration the accidents/species of bread and wine remain, without any substance/subject, through God’s miraculous intervention. (Cf. ST III, 77, 1&2; )

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