The Master Mind of Mars by Edgar Rice Burroughs

Three weeks passed rapidly. I had mastered enough of the Barsoomian tongue to enable me to converse with my host in a reasonably satisfactory manner, and I was also progressing slowly in the mastery of the written language of his nation, which is different, of course, from the written language of all other Barsoomian nations, though the spoken language of all is identical. In these three weeks I had learned much of the strange place in which I was half guest and half prisoner and of my remarkable host-jailer, Ras Thavas, the old surgeon of Toonol, whom I had accompanied almost constantly day after day until gradually there had unfolded before my astounded faculties an understanding of the purposes of the institution over which he ruled and in which he labored practically alone; for the slaves and attendants that served him were but hewers of wood and carriers of water. It was his brain alone and his skill that directed the sometimes beneficent, the sometimes malevolent, but always marvelous activities of his life's work.

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.