Appearances to the mind are of four kinds. Things either are what they appear to be; or they neither are, nor appear to be; or they are, and do not appear to be; or they are not, and yet appear to be. Rightly to aim in all these cases is the wise man's task.
What is a child? Ignorance. What is a child? Want of instruction.
All philosophy lies in two words, sustain and abstain.
No man is disturbed by things, but by his opinion about things.
It is difficulties that show what men are.
If any be unhappy, let him remember that he is unhappy by reason of himself alone. For God hath made all men to enjoy felicity and constancy of good.