litmus

Roughly speaking, most ordinary human virtues and vices may be detected by their different reactions to repetition.  The ordinary vices become numbing upon repetition, but continue to drain the actor.  The ordinary virtues build over repetition, and grow easier.  Or, to be more precise than the thought deserves: Vices are vices partly by virtue of having a diminishing return but constant incremental cost.  Virtues and virtues partly by virtue of having constant (or improving return) over diminishing incremental cost.

The obvious objection is that this is true only of most garden variety vices and virtues, and those are known to nearly all, so what's the use?  The response is that noticing that, in this context, gets us right to the question of whether virtues and vices - good and evil - have their own existence, or only live, like characters, by enactment within a given proscenium.