You charm'd me not with that fair face
Though it was all divine:
To be another's is the grace,
That makes me wish you mine.

The Gods and Fortune take their part
Who like young monarchs fight;
And boldly dare invade that heart
Which is another's right.

First mad with hope we undertake
To pull up every bar;
But once possess'd, we faintly make
A dull defensive war.

Now every friend is turn'd a foe
In hope to get our store:
And passion makes us cowards grow,
Which made us brave before.

John Dryden

http://www.poemhunter.com/poem/you-charm-d-me-not-with-that-fair-face/