Well, the conversation was not as profitless as it might appear, for I was sure that it had almost convinced Ras Thavas that I was equally as ignorant of the fate of Valla Dia as was he. That it had not wholly convinced him was evidenced by the fact that the espionage continued for a long time, a fact which determined me to use Ras Thavas’ own methods in my own defence. I had had allotted to me a number of slaves, and these I had won over by kindness and understanding until I knew that I had the full measure of their loyalty. They had no reason to love Ras Thavas and every reason to hate him; on the other hand they had no reason to hate me, and I saw to it that they had every reason to love me. The result was that I had no difficulty in enlisting the services of a couple of them to spy upon Ras Thavas’ spies, with the result that I was soon apprised that my suspicions were well founded—I was being constantly watched every minute that I was out of my apartments, but the spying did not come beyond my outer chamber walls. That was why I had been successful in reaching the vault in the manner that I had, the spies having assumed that I would leave my chamber only by its natural exit, had been content to guard that and permit my windows to go unwatched. I think it was about two of our months that the spying continued and then my men reported that it seemed to have ceased entirely. All that time I was fretting at the delay, for I wanted to be about my plans which would have been absolutely impossible for me to carry out if I were being watched. I had spent the interval in studying the geography of the north-eastern Barsoomian hemisphere where my activities were to be carried on, and also in scanning a great number of case histories and inspecting the subjects to which they referred; but at last, with the removal of the spies, it began to look as though I might soon commence to put my plans in active operation. Ras Thavas had for some time permitted me considerable freedom in independent investigation and experiment, and this I determined to take advantage of in every possible way that might forward my plans for the resurrection of Valla Dia. My study of the histories of many of the cases had been with the possibility in mind of discovering subjects that might be of assistance to me in my venture. Among those that had occupied my careful attention were, quite naturally, the cases with which I had been most familiar, namely: 378-J-493811-P, the red-man from whose vicious attack I had saved Ras Thavas upon the day of my advent upon Mars; and he whose brain had been divided with an ape.