Ras Thavas himself was as remarkable as the things he accomplished. He was never intentionally cruel; he was not, I am sure, intentionally wicked. He was guilty of the most diabolical cruelties and the basest of crimes; yet in the next moment he might perform a deed that if duplicated upon Earth would have raised him to the highest pinnacle of man’s esteem. Though I know that I am safe in saying that he was never prompted to a cruel or criminal act by base motives, neither was he ever urged to a humanitarian one by high motives. He had a purely scientific mind entirely devoid of the cloying influences of sentiment, of which he possessed none. His was a practical mind, as evidenced by the enormous fees he demanded for his professional services; yet I know that he would not operate for money alone and I have seen him devote days to the study of a scientific problem the solution of which could add nothing to his wealth, while the quarters that he furnished his waiting clients were overflowing with wealthy patrons waiting to pour money into his coffers. His treatment of me was based entirely upon scientific requirements. I offered a problem. I was either, quite evidently, not a Barsoomian at all, or I was of a species of which he had no knowledge. It therefore best suited the purposes of science that I be preserved and studied. I knew much about my own planet. It pleased Ras Thavas’ scientific mind to milk me of all I knew in the hope that he might derive some suggestion that would solve one of the Barsoomian scientific riddles that still baffle their savants; but he was compelled to admit that in this respect I was a total loss, not alone because I was densely ignorant upon practically all scientific subjects, but because the learned sciences on Earth have not advanced even to the swaddling-clothes stage as compared with the remarkable progress of corresponding activities on Mars. Yet he kept me by him, training me in many of the minor duties of his vast laboratory. I was entrusted with the formula of the “embalming fluid” and taught how to withdraw a subject’s blood and replace it with this marvellous preservative that arrests decay without altering in the minutest detail the nerve or tissue structure of the body. I learned also the secret of the few drops of solution which, added to the rewarmed blood before it is returned to the veins of the subject, revitalizes the latter and restores to normal and healthy activity each and every organ of the body. He told me once why he had permitted me to learn these things that he had kept a secret from all others, and why he kept me with him at all times in preference to any of the numerous individuals of his own race that served him and me in lesser capacities both day and night.