The Shakespeare-Oxford Society's Page of Oxford's Poems:
http://www.shakespeare-oxford.com/?p=125
What plague is greater than the grief of mind?
The grief of mind that eats in every vein;
In every vein that leaves such clots behind;
Such clots behind as breed such bitter pain;
So bitter pain that none shall ever find,
What plague is greater than the grief of mind.
(in Clark 20-21; cf. Ogburn and Ogburn 52; Ogburn 583)