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;
The ocean leaves stretches of shore exposed, but only briefly before it returns. Likewise, the speaker suggests that the “sad interim” in which an emotional connection is lacking will be again replaced with the tide of love. “Sad interim” here may refer to a period of either emotional estrangement, or actual physical separation between the poet and his lover. 

Sonnet 56