Alas, have I not pain enough, my friend,
Upon whose breast a fiercer gripe doth tire,
Than did on him who first stole down the fire,
While Love on me doth all his quiver spend,

But with your rhubarb words you must contend,
To grieve me worse, in saying that desire
Doth plunge my well-form'd soul even in the mire
Of sinful thoughts, which do in ruin end?

If that be sin which doth the manners frame,
Well stayed with truth in word and faith of deed,
Ready of wit and fearing nought but shame:

If that be sin which in fix'd hearts doth breed
A loathing of all loose unchastity,
Then love is sin, and let me sinful be.

Sir Philip Sidney

http://www.poemhunter.com/poem/sonnet-xiv-alas-have-i-not/