The belief that the substance (essence) of Christ's body and blood replaces the substance of the eucharistic bread and wine, although the appearances (known as "accidents" or "species") of the bread and wine continue outwardly unchanged. This eucharistic theology is based on the philosophical categories of Aristotle, elaborated at length by medieval Latin theologians, and regarded as definitive in the Roman Catholic tradition. The term is derived from the Latin trans "across" or "over," and substantia, "substance." The classical explanation of transubstantiation was presented by Thomas Aquinas in the Summa Theologica. Transubstantiation was also defended by the Fourth Lateran Council (1215) and the Council of Trent (1545-1563). Article XXVIII of the Articles of Religion rejected transubstantiation as "repugnant" and unscriptural, asserting instead that Christ is present in the eucharist in a "heavenly and spiritual manner" (BCP, p. 873). The English Test Act of 1673 required a Declaration Against Transubstantiation by all persons holding civil or military office. Some nineteenth-century Tractarians, such as John Henry Newman, found transubstantiation to be compatible with their understanding of the eucharist. But the concept of transubstantiation has generally been avoided and excluded from Anglican theologies of the Real Presence of Christ's body and blood in the eucharist. See Real Presence; see Receptionism.