The saying of Protagoras is like the views we have mentioned; he said that man is the measure of all things, meaning simply that that which seems to each man assuredly is. If this is so, it follows that the same thing both is and is not, and is bad and good, and that the contents of all other opposite statements are true, because often a particular thing appears beautiful to some and ugly to others, and that which appears to each man is the measure
And it is characteristic of man that he alone has any sense of good and evil, of just and unjust, and the like, and the association of living beings who have this sense makes family and a state.
Every formed disposition of the soul realizes its full nature in relation to and dealing with that class of objects by which it is its nature to be corrupted or improved.
The knowledge of the soul admittedly contributes greatly to the advance of truth in general, and, above all, to our understanding of Nature, for the soul is in some sense the principle of animal life.
Again, the male is by nature superior, and the female inferior; and the one rules, and the other is ruled; this principle, of necessity, extends to all mankind.
Now property is part of a household, and the acquisition of property part of household-management; for neither life itself nor the good life is possible without a certain minimum supply of the necessities.
The ensouled is distinguished from the unsouled by its being alive. Now since being alive is spoken of in many ways, even if only one of these is present, we say that the thing is alive, if, for instance, there is intellect or perception or spatial movement and rest or indeed movement connected with nourishment and growth and decay. It is for this reason that all the plants are also held to be alive . . .
Different men seek after happiness in different ways and by different means, and so make for themselves different modes of life and forms of government.