"How singular is the thing called pleasure, and how 

 curiously related to pain, which might be thought to be the op- 

 posite of it; for they never come to a man together, and yet 

 he who pursues either of them is generally compelled to take 

 the other. They are two, and yet they grow together out of 

 one head or stem." Socrates (in Plato 1 s Phczdo}. 



