Acting, to Don Luis Perenna, during those hours of forced inactivity, consisted solely in perpetually repeating to himself Gaston Sauverand’s account of the events.  He tried to reconstitute it in all its details, to remember the very least sentences, the apparently most insignificant phrases.  And he examined those sentences, scrutinized those phrases one by one, in order to extract such particle of the truth as they contained.

For the truth was there.  Sauverand had said so and Perenna did not doubt it.  The whole sinister affair, all that constituted the case of the Mornington inheritance and the tragedy of the Boulevard Suchet, all that could throw light upon the plot hatched against Marie Fauville, all that could explain the undoing of Sauverand and Florence—­all this lay in Sauverand’s story.  Don Luis had only to understand, and the truth would appear like the moral which we draw from some obscure fable.

Don Luis did not once deviate from his method.  If any objection suggested itself to his mind, he at once replied: 

“Very well.  It may be that I am wrong and that Sauverand’s story will not enlighten me on any point capable of guiding me.  It may be that the truth lies outside it.  But am I in a position to get at the truth in any other way?  All that I possess as an instrument of research, without attaching undue importance to certain gleams of light which the regular appearance of the mysterious letters has shed upon the case, all that I possess is Gaston Sauverand’s story.  Must I not make use of it?”

And, once again, as when one follows a path by another person’s tracks, be began to live through the adventure which Sauverand had been through.  He compared it with the picture of it which he had imagined until then.  The two were in opposition; but could not the very clash of their opposition be made to produce a spark of light?

“Here is what he said,” he thought, “and there is what I believed.  What does the difference mean?  Here is the thing that was, and there is the thing that appeared to be.  Why did the criminal wish the thing that was to appear under that particular aspect?  To remove all suspicion from him?  But, in that case, was it necessary that suspicion should fall precisely on those on whom it did?”

The questions came crowding one upon the other.  He sometimes answered them at random, mentioning names and uttering words in succession, as though the name mentioned might be just that of the criminal, and the words uttered those which contained the unseen reality.

Then at once he would take up the story again, as schoolboys do when parsing and analyzing a passage, in which each expression is carefully sifted, each period discussed, each sentence reduced to its essential value.

* * * * *

Hours and hours passed.  Suddenly, in the middle of the night, he gave a start.  He took out his watch.  By the light of his electric lamp he saw that it was seventeen minutes to twelve.