Can life be a blessing,
Or worth the possessing,
Can life be a blessing if love were away?
Ah no! though our love all night keep us waking,
And though he torment us with cares all the day,
Yet he sweetens, he sweetens our pains in the taking,
There's an hour at the last, there's an hour to repay.

In ev'ry possessing,
The ravishing blessing,
In ev'ry possessing the fruit of our pain,
Poor lovers forget long ages of anguish,
Whate'er they have suffer'd and done to obtain;
'Tis a pleasure, a pleasure to sigh and to languish,
When we hope, when we hope to be happy again.

John Dryden

http://www.poemhunter.com/poem/troilus-and-cressida/