"I see," said Isbister.

"I did my work," said the sleepless man with a querulous intonation.

"And this is the price?"

"Yes."

For a little while the two remained without speaking.

"You cannot imagine the craving for rest that I feel--a hunger and
thirst. For six long days, since my work was done, my mind has been a
whirlpool, swift, unprogressive and incessant, a torrent of thoughts
leading nowhere, spinning round swift and steady--" He paused. "Towards
the gulf."

"You must sleep," said Isbister decisively, and with an air of a remedy
discovered. "Certainly you must sleep."

"My mind is perfectly lucid. It was never clearer. But I know I am
drawing towards the vortex. Presently--"

"Yes?"

"You have seen things go down an eddy? Out of the light of the day, out
of this sweet world of sanity--down--"

"But," expostulated Isbister.