In the Middle Ages, Catholic philosophers elaborated the thought that there exist transcendentals ("transcendentalia") and that they transcended each of the ten Aristotelian categories. A doctrine of the transcendentality of the good was formulated by Albert the Great. His pupil, Saint Thomas Aquinas, posited five transcendentals: "res, unum, aliquid, bonum, verum"; or "thing", "one", "something", "good", and "true". Saint Thomas derives the five explicitly as transcendentals, though in some cases he follows the typical list of the transcendentals consisting of the One, the Good, and the True. The transcendentals are ontologically one and thus they are convertible: e.g., where there is truth, there is beauty and goodness also.