Sweet love renew thy force, be it not said
Thy edge should blunter be than appetite,
Which but to-day by feeding is allayed,
To-morrow sharpened in his former might.
So love be thou, although to-day thou fill
Thy hungry eyes, even till they wink with fulness,
To-morrow see again, and do not kill
The spirit of love, with a perpetual dulness:
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.
Or 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-said/