Virtue, then, is a state of character concerned with choice, lying ina mean†it is a mean between twovices, that which depends on excess and that which depends on defect.

-Aristotle
Nicomachean Ethics, bk.2, ch.6,1006 (translated by Sir David Ross).

I have known no man of genius who had not to pay, in some affliction or defect either physical or spiritual, for what the gods had given him.

-Beerbohm, Sir (Henry) Max(imilian)
  And Even Now,'The Pines'.

The chief defect of Henry King Was chewing little bits of string.

-Belloc, (Joseph) Hilaire Pierre
  Cautionary  Tales,'Henry King'.

L'histoire est condamne¤  e, par un vice de nature, au mensonge. History is condemned, bya defect of nature, to lies.

-Thibault
  La Vie litte¤  raire, pt.17.

It is a fatal defect of current principles of administration that, like proverbs, they occur in pairs. For almost every principle one can find an equally plausible and acceptable contradictory principle. Although the two principles of the pair will lead to exactly opposite recommendations, there is nothing in the theory to indicate which is the appropriate one to apply.

-Simon, Herbert A
  Administrative Behavior.