As often as he reached the stage at which he imagined Paolo dead, hidden, and buried in a cellar, the same shiver passed through him as he glanced involuntarily behind him.

Why?
What power could a dead body possibly exercise over a living man in the full possession of his senses?
Here was something which Marzio could not understand, but of which he was made aware by his own feelings.

The difficulty only increased in magnitude as he faced it, considered it, and tried to view it from all its horrible aspects.

But he could not overcome it.

He might laugh at the existence of the soul and jest about the future state after death; he could not escape from the future in this life if he did the deed he contemplated.