When I was in grad school and first took a deep look at St. Thomas Aquinas’s articulation of transubstantiation, I was surprised at what I encountered. I had, to that point, imagined that “physically” was an apt adverb to describe Christ’s presence in the Eucharist. But when I used this descriptor rather casually in a meeting with a professor, I was pointed to Aquinas’s Summa Theologica, among other sources in the Church’s tradition. What I found there was not a description of a physical presence — at least, not in the sense we would usually understand such terms — but of a presence that was, in fact, much more than physical.
Recently, I have had several encounters with theology professors who report the same thing in their students. The students come in thinking that what the Church means by Real Presence is some kind of physical presence. And so, for example, they are often surprised to learn that St. Thomas would not expect researchers to find anything other than (the accidents of) bread and wine if the consecrated elements were subjected to some kind of scientific analysis.
More real than physical
For contemporary people, “physical” is often just another way of saying “real.” But this is not a Catholic view of the world. Surely there are real things that aren’t physical. Truth, for instance, or God. Even when it comes to those very physical sacraments that Jesus left his Church, people know that something much deeper is going on. Almost no one thinks, for example, that we could somehow distinguish between a baptized and an unbaptized person in a lab. But we do not therefore doubt that baptism does something real.
The doctrine of transubstantiation, which, in the popular imagination, often buttresses a kind of physical Eucharistic presence, was actually developed to counter such imaginings. Just like today, in the century before St. Thomas wrote, people were debating Christ’s eucharistic presence. And there were two basic options before them. The first was a kind of covert physical change. The second was the notion that the elements of bread and wine merely symbolized Christ’s presence. Both of these were quite inadequate to articulate the Church’s faith in the Eucharist.
While it might seem obvious that the second option represents a reduction of that faith, Aquinas and others insisted that both options were reductions, if in different ways. The second reduces the Eucharist to what goes on in our own heads. But the first reduces what goes on in the Eucharist to the physical order. Transubstantiation was developed to articulate something deeper than either of these, something at the level of reality, which is more than merely physical.
Perceiving reality with our minds
To see just how transubstantiation manages to do this, we need to think about the category at its heart: substance. While some critics suggest that transubstantiation is outdated because it relies on philosophical categories from Aristotle, a little reflection shows that “substance” is actually describing a fairly common-sense thing that we all take for granted in our encounters with and descriptions of the world.
Take a river, for example. Now, geologists can tell you how old a given river is. But when they do so, they are presuming that a river today is the same thing as a river yesterday, and for hundreds or thousands of years before that. But rivers are always in flux. The water in a river changes not just from day to day, but from minute to minute. The banks and bed shift subtly all the time, and even the valleys in which rivers flow change dramatically over the years. What is it, then, that allows us to identify a given river over time despite dramatic changes in its physical makeup?
Our own bodies are not so different. We all started as single-celled organisms, but we go through radical changes over our lifespan, cycling through all the cells in our bodies every seven years or so. But we can still identify an 85-year-old with a single cell that began in his mother’s womb decades earlier. How?
There must be, or so all our language presumes, some underlying reality, some identifiable principle of unity, that we can perceive, not with our senses, but with our minds. What we perceive with our senses changes day to day, but our minds can still know that this river remains this river and that person remains that person. This should help us understand what St. Thomas means when he defines an “accident” as that which is present to the senses and “substance” as that which is present to the mind. The physical, that which our senses perceive, does not change in the Eucharist, but the substance, which our minds can identify when we hear and believe the words of consecration, does.
What the tradition found in transubstantiation was a solution to the false dichotomy between a merely physical or a merely symbolic presence of Christ in the Eucharist. A change of substance is a change at the deepest level of created reality. It is a change in what makes something the kind of thing that it is. For St. Thomas, it is an act whose best analogy is creation itself.
