(1) Things that are different are not mutually convertible. (2) But thought and being in its proper sense (i.e. being as substance) are different. As Aristotle says, truth and falsity do not belong to being in its proper sense: "For falsity and truth are not in things — it is not as if the good were true, and the bad were in itself false — but in thought…"¹ "But since the combination and the separation are in thought and not in things, and that which is in this sense is a different sort of "being" from the things that are in the full sense …"² (3) Thus being and truth are not mutually convertible.