n which he had spent
so many prosperous years. There had, indeed, been some coldly angry
words between the two men. Marcello had told Folco quite plainly that he
meant to be the master, and that he was of age, and should regulate his
own life as he pleased, and he had expressed considerable disgust at the
existence Folco had been leading in Paris and elsewhere; and Folco had
always tried to laugh it off, calling Marcello prudish and
hypersensitive in matters of morality, which he certainly was not. Once
he had attempted an appeal to Marcello's former affection, recalling
his mother's love for them both, but a look had come into the young
man's eyes just then which even Corbario did not care to face again, and
the relations between the two had become more strained from that time
on.

It might seem almost incredible that a man capable of the crimes
Corbario had committed in cold blood, for a settled purpose, should show
so little power of following the purpose to its accomplishment after
clearing the way to it by a murder; but every one who has had to do with
criminals is aware that after any great exertion of destructive energy
they are peculiarly subject to a long reaction of weakness which very
often leads to their own destruction. If this were not a natural law, if
criminals could exert continually the same energy and command the same
superhuman cunning which momentarily helped them to perpetrate a crime,
the world would be in danger of being possessed and ruled by them,
instead of being mercifully, and perhaps too much, inclined to treat
them as degenerates and madmen. Their conduct after committing a murder,
for instance, seems to depend much more on their nerves than on their
intelligence, and the time almost invariably comes when their nerves
break down. It is upon the moment when this collapse of the will sets in
that the really experienced detective counts, knowing that it may be
hastened or retarded by circumstances quite beyond the murderer's
control. The life of a murderer, after the deed, is one long fight with
such circumstances, and if he once loses his coolness he is himself
almost as surely lost as a man who is carried away by his temper in a
duel with swords.

After Folco had killed his wife and had just failed to kill Marcello, he
had behaved with wonderful calm and propriety for a little while; but
before long the old wild longing for excitement and dissipation, so long
kept down during his married