The professor's first step was to recall as many of his books as
possible; his second to close his laboratory and stop all research. He
gave no explanation, he invited no questions. His whole personality
crumbled away, so to speak, till his daily life became a mere mechanical
process of clothing the body, feeding the body, keeping it in good
health so as to avoid physical discomfort, and, above all, doing nothing
that could interfere with sleep. The professor did everything he could
to lengthen the hours of sleep, and therefore of forgetfulness.

It was all clear enough to Dr. Laidlaw. A weaker man, he knew, would
have sought to lose himself in one form or another of sensual
indulgence--sleeping-draughts, drink, the first pleasures that came to
hand. Self-destruction would have been the method of a little bolder
type; and deliberate evil-doing, poisoning with his awful knowledge all
he could, the means of still another kind of man. Mark Ebor was none of
these. He held himself under fine control, facing silently and without
complaint the terrible facts he honestly believed himself to have been
unfortunate enough to discover. Even to his intimate friend and
assistant, Dr. Laidlaw, he vouchsafed no word of true explanation or
lament. He went straight forward to the end, knowing well that the end
was not very far away.

And death came very quietly one day to him, as he was sitting in the
arm-chair of the study, directly facing the doors of the laboratory--the
doors that no longer opened. Dr. Laidlaw, by happy chance, was with him
at the time, and just able to reach his side in response to the sudden
painful efforts for breath; just in time, too, to catch the murmured
words that fell from the pallid lips like a message from the other side
of the grave.