“The choice of these books surprises you a bit?”

“I can’t say it surprises me,” I replied, “since I don’t know the nature of the work for which you have collected them.  In any case I dare say, without fear of being contradicted, that never before has officer of the Arabian Office possessed a library in which the humanities were so, well represented.”

He smiled evasively, and that day we pursued the subject no further.

Among Saint-Avit’s books I had noticed a voluminous notebook secured by a strong lock.  Several times I surprised him in the act of making notations in it.  When for any reason he was called out of the room he placed his album carefully in a small cabinet of white wood, provided by the munificence of the Administration.  When he was not writing and the office did not require his presence, he had the mehari which he had brought with him saddled, and a few minutes later, from the terrace of the fortifications, I could see the double silhouette disappearing with great strides behind a hummock of red earth on the horizon.

Each time these trips lasted longer.  From each he returned in a kind of exaltation which made me watch him with daily increasing disquietude during meal hours, the only time we passed quite alone together.

“Well,” I said to myself one day when his remarks had been more lacking in sequence than usual, “it’s no fun being aboard a submarine when the captain takes opium.  What drug can this fellow be taking, anyway?”

Next day I looked hurriedly through my comrade’s drawers.  This inspection, which I believed to be my duty, reassured me momentarily.  “All very good,” I thought, “provided he does not carry with him his capsules and his Pravaz syringe.”

I was still in that stage where I could suppose that Andre’s imagination needed artificial stimulants.

Meticulous observation undeceived me.  There was nothing suspicious in this respect.  Moreover, he rarely drank and almost never smoked.

And nevertheless, there was no means of denying the increase of his disquieting feverishness.  He returned from his expeditions each time with his eyes more brilliant.  He was paler, more animated, more irritable.

One evening he left the post about six o’clock, at the end of the greatest heat of the day.  We waited for him all night.  My anxiety was all the stronger because quite recently caravans had brought tidings of bands of robbers in the neighborhood of the post.

At dawn he had not returned.  He did not come before midday.  His camel collapsed under him, rather than knelt.

He realized that he must excuse himself, but he waited till we were alone at lunch.

“I am so sorry to have caused you any anxiety.  But the dunes were so beautiful under the moon!  I let myself be carried farther and farther....”

“I have no reproaches to make, dear fellow, you are free, and the chief here.  Only allow me to recall to you certain warnings concerning the Chaamba brigands, and the misfortunes that might arise from a Commandant of a post absenting himself too long.”