'Love seeketh not itself to please,
Nor for itself hath any care,
But for another gives its ease,
And builds a heaven in hell's despair.'

So sung a little clod of clay,
Trodden with the cattle's feet;
But a pebble of the brook
Warbled out these meters meet:

'Love seeketh only Self to please,
To bind another to its delight,
Joys in another's loss of ease,
And builds a hell in heaven's despite.'

William Blake

http://www.poemhunter.com/poem/the-clod-and-the-pebble/