The transcendentals are the properties of being. In typical accounts being is said to be One, Good and True (unum, bonum, verum). Additional properties such as Thing, Beautiful and Being (ens) are often posited as transcendentals but remain more disputed.
It was Parmenides who first explored the properties co-extensive with being. Plato then followed. However, it is in Aristotle we first see the term transcendentals used. They were so called as they transcended (ὑπερβαίνειν huperbainein) each of his ten categories. Aristotle treat only of unity ("One") explicitly because it is the only transcendetal intrinsically related to being, whereas truth and goodness relate to rational creatures.[1]
St. Thomas Aquinas listed five transcendentals: res, unum, alquid, bonum, verum.[2] Saint Thomas does not list these as transcendentals, at least not in the cited source. He follows the typical account of the transcendentals consisting of the One, Good, and True.
The transcendentals are ontologically one, thus they are convertible. Where there is truth, there is beauty and goodness also.
In Christian theology the transcendentals are treated in relation to Theology Proper, the doctrine of God. The transcendentals, according to Christian doctrine, can be described as the ultimate desires of man. Man ultimately strives for perfection, which takes form through the desire for perfect attainment of the transcendentals.
Each transcends the limitations of place and time, and are rooted in being. The transcendentals are not contingent upon cultural diversity, religious doctrine, or personal ideologies, but are the objective features of all that is.