Transubstantiation
According to the Catholic Church, when the bread and wine are consecrated by the priest at Mass, they cease to be bread and wine, and become instead the Most Precious Body and Blood of Christ. The empirical appearances and attributes are not changed, but the underlying reality is. The consecration of the bread (known afterwards as the Host) and wine represents the separation of Jesus' body from his blood at Calvary; thus, this separation also represents the death of Christ. However, since according to Catholic dogma Christ has risen, the Church teaches that his body and blood are no longer truly separated, even if the appearances of the bread and the wine are. Where one is, the other must be. This is called the doctrine of concommitance. Therefore, although the priest (or minister) says, "The body of Christ", when administering the host, and, "The blood of Christ", when presenting the chalice, the communicant who receives either one receives Christ, whole and entire— "Body, Blood, Soul, and Divinity".
Transubstantiation (from Latin transsubstantiatio) is the change of the substance of bread and wine into that of the body and blood of Christ, the change that, according to the belief of the Catholic Church, occurs in the Eucharist. It concerns what is changed (the substance of the bread and wine), not how the change is brought about.
"Substance" here means what something is in itself. (For more on the philosophical concept, see Substance theory.) A hat's shape is not the hat itself, nor is its colour the hat, nor is its size, nor its softness to the touch, nor anything else about it perceptible to the senses. The hat itself (the "substance") has the shape, the colour, the size, the softness and the other appearances, but is distinct from them. Whereas the appearances, which are referred to by the philosophical term accidents are perceptible to the senses, the substance is not.
When at his Last Supper Jesus said: "This is my body", what he held in his hands had all the appearances of bread. However, the Catholic Church teaches that the underlying reality was changed in accordance with what Jesus said, that the "substance" of the bread was converted to that of his body. In other words, it actually was his body, while all the appearances open to the senses or to scientific investigation were still those of bread, exactly as before. The Church believes that the same change of the substance of the bread and of the wine occurs at every Catholic Mass throughout the world.
The Catholic Church accordingly believes that through transubstantiation Christ is really, truly and substantially present under the remaining appearances of bread and wine, and that the transformation remains as long as the appearances remain. For this reason the consecrated elements are preserved, generally in a church tabernacle, for giving Holy Communion to the sick and dying, and also for the secondary, but still highly lauded, purpose of adoring Christ present in the Eucharist.
In the judgment of the Catholic Church, the concept of transubstantiation, with its accompanying unambiguous distinction between "substance" or underlying reality, and "accidents" or humanly perceptible appearances, safeguards against what it sees as the mutually opposed errors of, on the one hand, a merely figurative understanding of the Real Presence of Christ in the Eucharist (the change of the substance is real), and, on the other hand, an interpretation that would amount to cannibalistic (a charge which pagans leveled at early Catholic Christians who did not understand the rites of the Catholic Church in that it was considered an "unbloody sacrifice") eating of the flesh and corporal drinking of the blood of Christ (the accidents that remain are real, not an illusion) and that Christ is "really, truly, and substantially present" in the Eucharist, not physically present, as he was physically present in the Judea of two millennia ago).
Some put forward the idea that transubstantiation is a concept intelligible only in terms of Aristotelian philosophy. But the earliest known use of the term "transubstantiation" to describe the change from bread and wine to body and blood of Christ was by Hildebert de Savardin, Archbishop of Tours (died 1133) in about 1079, long before the Latin West, under the influence especially of Saint Thomas Aquinas (c. 1227-1274), accepted Aristotelianism. (The University of Paris was founded only between 1150 and 1170.) The term "substance" (substantia) as the reality of something was in use from the earliest centuries of Latin Christianity, as when they spoke of the Son as being of the same "substance" (consubstantialis) as the Father. The corresponding Greek term is "οὐσία" the Son is said to be "ὁμοούσιος" with the Father and the change of the bread and wine into the body and blood of Christ is called "μετουσίωσις". The doctrine of transubstantiation is thus independent of Aristotelian philosophical concepts, and these were not and are not dogmata of the Church.
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