To thirst and find no fill—to wail and wander
With short unsteady steps—to pause and ponder--
To feel the blood run through the veins and tingle
Where busy thought and blind sensation mingle;
To nurse the image of unfelt caresses
Till dim imagination just possesses
The half-created shadow, then all the night
Sick...

Percy Bysshe Shelley

http://www.poemhunter.com/poem/fragment-igniculus-desiderii/