Men pay most attention to what is their own: they care less for what is common; or, at any rate, they care for it only to the extent to which each is individually concerned.
We maintain, and have said in the Ethics, if the arguments there adduced are of any value, that happiness is the realization and perfect exercise of virtue, and this not conditional, but absolute. And I used the term 'conditional' to express that which is indispensable, and 'absolute' to express that which is good in itself.
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
The investigation of the truth is in one way hard, in another easy. An indication of this is found in the fact that no one is able to attain the truth adequately, while, on the other hand, no one fails entirely, but everyone says something true about the nature of all things, and while individually they contribute little or nothing to the truth, by the union of all a considerable amount is amassed.
The tyrant, who in order to hold his power, suppresses every superiority, does away with good men, forbids education and light, controls every movement of the citizens and, keeping them under a perpetual servitude, wants them to grow accustomed to baseness and cowardice, has his spies everywhere to listen to what is said in the meetings, and spreads dissension and calumny among the citizens and impoverishes them, is obliged to make war in order to keep his subjects occupied and impose on them permanent need of a chief.