Meditations

but those who do not observe the movements of their own minds must of necessity be unhappy.

For the present is the only thing of which a man can be deprived, if it is true that this is the only thing which he has, and that a man cannot lose a thing if he has it not.

that he was able both to abstain from, and to enjoy, those things which many are too weak to abstain from, and cannot enjoy without excess.

and to read carefully, and not to be satisfied with a superficial understanding of a book;

Since it is possible[A] that thou mayest depart from life this very moment, regulate every act and thought accordingly.[B]