Sweet love, renew thy force! Be it not said
Thy edge should blunter be than appetite,
Which but today by feeding is allayed,
Tomorrow sharpened in his former might.
So, love, be thou, although today thou fill
Thy hungry eyes, even till they wink with fulness,
Tomorrow see again, and do not kill
The spirit of love with a perpetual dullness.
Let this sad interim like the ocean be
Which parts the shore where two contracted new
Come daily to the banks, that, when they see
Return of love, more blest may be the view;
As call it winter, which being full of care
Makes summer's welcome thrice more wished, more rare.

William Shakespeare

http://www.poemhunter.com/poem/sonnet-56-sweet-love-renew-thy-force-be-it-not-s/