Many commentators have accused Aquinas of committing either a formal or an informal fallacy in his Third Way argument. I believe it is possible to revise the Third Way argument so as to avoid such errors. I here present a revision of the first part of the Third Way that is (a) immune to the objections most commonly raised against it, (b) consonant with the basic tenets of Thomism, and (c) plausible from a contemporary point of view.