Roman Catholic Eucharistic Doctrine draws upon a quasi-Aristotelian understanding of reality, in which the core substance or essential reality of a given thing is bound to, but not equivalent with, its sensible realities or accidents. In the celebration of the Eucharist, by means of the consecratory Eucharistic Prayer, the actual substance of the bread and wine are changed into the body and blood of Christ. This change in substance is not, however, the outward appearances of the bread and wine—their accidents—which remain as before. This substantial change is called transubstantiation, a term reserved to describe the change itself. Scholastic philosophical terminology was used but is not a part of the dogma that defined Christ's presence for the Roman Catholic Church at the Council of Trent. In the 13th session of 11 October 1551, it promulgated the following conciliar decree: "if anyone says that the substance of bread and wine remains in the Holy Sacrament of the Eucharist together with the Body and