Desire

Quoting Todd McGowan in a fascinating book (a Lacanian interpretation of David Lynch' s films):

"The desiring subject doesn't know what it wants because it wants nothing - the impossible object that exists only insofar as it remains inaccessible. This is why the anorexic who literally eats the nothing is in some sense the pure subject of desire. The subject who can name what it wants has accepted a fantasmatic substitute for this nothing."

("The Impossible David Lynch", New York, Columbia University Press, p. 100)