Immature poets imitate; mature poets steal; bad poets deface what they take, and good poets make it into something better, or at least something different.

-Eliot,T(homas) S(tearns)
  The Sacred Wood,'Philip Massinger'.

The imagination of a boy is healthy, and the mature imagination of a man is healthy; but there is a space of life between, in which the soul is in a ferment, the character undecided, the way of life uncertain, the ambition thick-sighted: thence proceeds mawkishness.

-Keats,John
  Endymion, preface.

It may almost be a question whether such wisdom as many of us have in our mature years has not come from the dying out of the power of temptation, rather than as the results of thought and resolution.

-Trollope, Anthony
  The Small House at Allington, ch.14.