Anything whose presence or absence makes no discernible difference is no essential part of the whole.
AristotleBut the virtues we get by first exercising them, as also happens in the case of the arts as well. For the things we have to learn before we can do them, we learn by doing them, e.g. men become builders by building and lyre players by playing the lyre; so too we become just by doing just acts, temperate by doing temperate acts, brave by doing brave acts.
AristotleThou wilt find rest from vain fancies if thou doest every act in life as though it were thy last.
Aristotle