And therefore if to love can be desert,  
I am not all unworthy. Cheeks as pale  
As these you see, and trembling knees that fail  
To bear the burden of a heavy heart,--  
This weary minstrel-life that once was girt  
To climb Aornus, and can scarce avail  
To pipe now 'gainst the valley nightingale  
A melancholy music,--why advert  
To these things? O Belovèd, it is plain  
I am not of thy worth nor for thy place!  
And yet, because I love thee, I obtain  
From that same love this vindicating grace,  
To live on still in love, and yet in vain,--  
To bless thee, yet renounce thee to thy face.
Elizabeth Barrett Browning
http://www.poemhunter.com/poem/sonnet-xi-and-therefore-if-to-love/