Had he been in the act of turning?
Had he turned far enough to see before the blow had extinguished memory?
How far was the sudden going out of thought really instantaneous?
What fraction of a second intervened between full life and what was so like death?
How long did it take a man to look round quickly?
Much less than a second, surely! Without effort or hurry a man could turn his head all the way from left to right, so as to look over each shoulder alternately, while a second pendulum swung once.

A second was a much longer time than most people realised.

Instruments made for scientific photography could be made to expose the plate not more than one-thousandth of a second.

Corbario knew that, and wondered whether a man's eye could receive any impression in so short a time.

He shuddered when he thought that it might be possible.
The question was to be answered sooner than he expected.