Quo usque tandem abutere, Catalina, patientia nostra? - Cicero

The man who backbites an absent friend, nay, who does not stand up for him when another blames him, the man who angles for bursts of laughter and for the repute of a wit, who can invent what he never saw, who cannot keep a secret — that man is black at heart: mark and avoid him.

So it may well be believed that when I found him taking a complete holiday, with a vast supply of books at command, he had the air of indulging in a literary debauch, if the term may be applied to so honorable an occupation.

Two distinctive traits especially identify beyond a doubt a strong and dominant character. One trait is contempt for external circumstances, when one is convinced that men ought to respect, to desire, and to pursue only what is moral and right, that men should be subject to nothing, not to another man, not to some disturbing passion, not to Fortune.
The second trait, when your character has the disposition I outlined just now, is to perform the kind of services that are significant and most beneficial; but they should also be services that are a severe challenge, that are filled with ordeals, and that endanger not only your life but also the many comforts that make life attractive.

Of these two traits, all the glory, magnificence, and the advantage, too, let us not forget, are in the second, while the drive and the discipline that make men great are in the former.