It is a significant circumstance that the 'suitable' is the lineal ancestor of our word 'duty' (through the Latin _officium_).
It was a great point with the Stoic to be conscious of 'advance' or improvement.[11] By self-examination, he kept himself constantly acquainted with his moral state, and it was both his duty and his satisfaction to be approaching to the ideal of the perfect man.
It is very illustrative of the unguarded points and contradictions of Stoicism, that contentment and apathy were not to permit grief even for the loss of friends.

Seneca, on one occasion, admits that he was betrayed by human weakness on this point.

On strict Stoical principles, we ought to treat the afflictions and the death of others with the same frigid indifference as our own; for why should a man feel for a second person _more_ than he ought to feel for himself, as a mere unit in the infinitude of the Universe?
This is the contradiction inseparable from any system that begins by abjuring pleasure, and relief or protection from pain, as the ends of life.

Even granting that we regard pleasure and relief from pain as of no importance in our own case, yet if we apply the same measure to others we are bereft of all motives to benevolence; and virtue, instead of being set on a loftier pinnacle, is left without any foundation.
EPICURUS.

[311--270 B.C.] Epicurus was born 341 B.C.in the island of Samos.