In this paper I wish to set forth as plainly and simply as possible a theory of the good which finds little modern vogue, but which nevertheless seems to me more plausible than any of those now current. The perfection theory of the good can claim weighty historical roots, especially in Plato and Aristotle; but I shall proceed systematically rather than historically. The exposition of the theory will be presented in three parts: first, a statement of a generic definition of perfection; second, an attempt to give more specific content to the definition; and third, an indication of my reasons for upholding the truth of the theory.