§ i. I propose to discuss what is called and appears to be moral virtue (which differs mainly from contemplative virtue in that it has emotion for its matter, and reason for its form), what its nature is, and how it subsists, and whether that part of the soul which takes it in is furnished with reason of its own, or participates in something foreign, and if the latter, whether as things that are mixed with something better than themselves, or rather as that which is subject to superintendence and command, and may be said to share in the power of that which commands. For I think it is clear that virtue can exist and continue altogether free from matter and mixture. My best course will be to run briefly over the views of others, not so much to display my research as because, when their ideas have been set forth, mine will become more clear and be on a firmer basis.
§ ii. Menedemus of Eretria took away the number and differences of virtues, on the ground that virtue was one though it had many names; for that just as mortal is synonymous with man, so temperance and bravery and justice were the same thing. And Aristo of Chios also made virtue one in substance, and called it soundness of mind: its diversities and varieties only existing in certain relations, as if one called our sight when it took in white objects white-sight, and when it took in black objects black-sight, and so on. For virtue, when it considers what it ought to do and what it ought not to do, is called prudence; and when it curbs passion, and sets a fit and proper limit to pleasure, it is called self-control; and when it is associated with our dealings and covenants with one another, it is called justice; just as a knife is one article, though at different times it cuts different things in half: and so, too, fire acts on different