Although St. Thomas Aquinas holds that the transcendentals are convertible with being, one may question whether they all follow upon the metaphysical principles of a creature in the same way. Aquinas raises the question when he says that creatures are one by essence but good only by being. This paper examines the ground of truth according to Aquinas, considering his distinction between types of truth as well as his distinguishing kinds of knowers. To advance this investigation the essay compares truth and goodness; it also includes a discussion of unity.

Clearly there is a close parallel between goodness and ‘the truth of a thing’, but must the truth of the intellect – truth in the primary sense – be grounded in the extramental being of a creature? This paper argues that, for Aquinas, human knowledge of composite beings is attained through encounters with their real instances and is reflected in necessarily true yet nonanalytic statements about these creatures, statements that can be explained by St.Thomas's theory of predication, to which the theory of an influential contemporary thinker is strikingly similar. God's knowledge of finite essences, and hence truth concerning them, does not assume the actual existence of their instantiations from all eternity, but it does assume their real existence at some time. The requirement of real existence for the human mode of knowing, and, as explained, for divine knowing, underscores the value of finite being and thus harmonizes with Aquinas's claims that composite beings, as what they are, possess being more truly in themselves than as in the mind of God, and they are known properly by God only when grasped as actually existent particulars.