Doubt is the beginning of wisdom

Aristotle said: "Evil brings men together."

Men regard it as their right to return evil for evil and, if they cannot, feel they have lost their liberty.

Happiness does not lie in amusement; it would be strange if one were to take trouble and suffer hardship all one's life in order to amuse oneself.

Plato is my friend, but truth is a better friend.

When there is no middle class, and the poor greatly exceed in number, troubles arise, and the state soon comes to an end.

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