He who is calm disturbs neither himself nor others.
I was not, I was, I am not, I care not. It's a Latin saying found on Roman grave markers. It means I wasn't bothered about not existing before I existed and I'm not bothered about not existing now that I don't exist.
One who understands the limits of the good life knows that what eliminates the pains brought on by need and what makes the whole of life perfect is easily obtained, so that there is no need for enterprises that entail the struggle for success.
Both old and young alike ought to seek wisdom: the former in order that, as age comes over him, he may be young in good things because of the grace of what has been, and the latter in order that, while he is young, he may at the same time be old, because he has no fear of the things which are to come.