Make no man your friend before inquiring how he has used his former friends; for you must expect him to treat you as he has treated them. Be slow to give your friendship, but when you have given it, strive to make it lasting; for it is as reprehensible to make many changes in one's associates as to have no friends at all. Neither test your friends to your own injury nor be willing to forego a test of your companions.
IsocratesLet there be but two occasions for speech - when the subject is one which you thoroughly know and when it is one on which you are compelled to speak. On these occasions alone is speech better than silence; on all others, it is better to be silent than to speak.
IsocratesAnd let no one suppose that I claim that just living can be taught for, in a word, I hold that there does not exist an art of the kind which can implant sobriety and justice into depraved natures. Nevertheless, I do think that the study of political discourse can help more than any other thing to stimulate and form such qualities of character
IsocratesIt is more important to know where you are going than to get there quickly. Do not mistake activity for achievement. Remember that there is nothing stable in human affairs, therefore avoid undue elation in prosperity or undue depression in adversity.
IsocratesAlways when you are about to say anything, first weigh it in your mind; for with many the tongue outruns the thought.
Isocrates