The strong man's hand, the snow-cool head of age,
The certain-footed sympathies of youth -
These, and that lofty passion after truth,
Hunger unsatisfied in priest or sage
Or the great men of former years, he needs
That not unworthily would dare to sing
(Hard task!) black care's inevitable ring
Settling with years upon the heart that feeds
Incessantly on glory. Year by year
The narrowing toil grows closer round his feet;
With disenchanting touch rude-handed time
The unlovely web discloses, and strange fear
Leads him at last to eld's inclement seat,
The bitter north of life - a frozen clime.

Robert Louis Stevenson

http://www.poemhunter.com/poem/sonnet-vii-2/