"What a narrow ridge of normality we all inhabit, with the abysses of mania and depression yawning to either side."

Oliver Sacks on mania.

IN THE COMMENTS: rhhardin says:

"Yawning'' is boredom.

Ha ha. Makes me think of Seinfeld:

George: I dunno, Jerry something's missing. There's a void, Jerry, there's a void...

Jerry: A deep, yawning chasm...