Days ran into weeks, weeks into months, as day by day I labored at the side of Ras Thavas, and more and more the old surgeon took me into his confidence, more and more he imparted to me the secrets of his skill and his profession.

Gradually he permitted me to perform more and more important functions in the actual practice of his vast laboratory. I started transferring limbs from one subject to another, then internal organs of the digestive tract. Then he entrusted to me a complete operation upon a paying client I removed the kidneys from a rich old man, replacing them with healthy ones from a young subject The following day I gave a stunted child new thyroid glands. A week later I transferred two hearts and then, at last, came the great day for me--unassisted, with Ras Thavas standing silently beside me, I took the brain of an old man and transplanted it within the cranium of a youth.

When I had done Ras Thavas laid a hand upon my shoulder. "I could not have done better myself," he said. He seemed much elated and I could not but wonder at this unusual demonstration of emotion upon his part, he who so prided himself upon his lack of emotionalism. I had often pondered the purpose which influenced Ras Thavas to devote so much time to my training, but never had I hit upon any more satisfactory explanation than that he had need of assistance in his growing practice. Yet when I consulted the records, that were now open to me, I discovered that his practice was no greater than it had been for many years; and even had it been there was really no reason why he should have trained me in preference to one of his red-Martian assistants, his belief in my loyalty not being sufficient warrant, in my mind, for this preferment when he could, as well as not have kept me for a bodyguard and trained one of his own kind to aid him in his surgical work.

But I was presently to learn that he had an excellent reason for what he was doing--Ras Thavas always had an excellent reason for whatever he did. One night after we had finished our evening meal he sat looking at me intently as he so often did, as though he would read my mind, which, by the way, he was totally unable to do, much to his surprise and chagrin; for unless a Martian is constantly upon the alert any other Martian can read clearly his every thought; but Ras Thavas was unable to read mine. He said that it was due to the fact that I was not a Barsoomian. Yet I could often read the minds of his assistants, when they were off their guard, though never had I read aught of Ras Thavas' thoughts, nor, I am sure, had any other read them. He kept his brain sealed like one of his own blood jars, nor was he ever for a moment found with his barriers down.

He sat looking at me this evening for a long time, nor did it in the least embarrass me, so accustomed was I to his peculiarities. "Perhaps," he said presently, "one of the reasons that I trust you is due to the fact that I cannot ever, at any time, fathom your mind; so, if you harbor traitorous thoughts concerning me I do not know it, while the others, every one of them, reveal their inmost souls to my searching mind and in each one there is envy, jealousy or hatred of me. Them, I know, I cannot trust. Therefore I must accept the risk and place all my dependence upon you, and my reason tells me that my choice is a wise one--I have told you upon what grounds it based my selection of you as my bodyguard. The same holds true in my selection of you for the thing I have in mind. You cannot harm me without harming yourself and no man will intentionally do that; nor is there any reason why you should feel any deep antagonism towards me.

"You are, of course, a sentimentalist and doubtless you look with horror upon many of the acts of a sane, rational, scientific mind; but you are also highly intelligent and can, therefore, appreciate better than another, even though you may not approve them, the motives that prompt me to do many of those things of which your sentimentality disapproves. I may have offended you, but I have never wronged you, nor have I wronged any creature for which you might have felt some of your so-called friendship or love. Are my premises incorrect, or my reasoning faulty?"

I assured him to the contrary.

"Very well! Now let me explain why I have gone to such pains to train you as no other human being, aside from myself, has ever been trained. I am not ready to use you yet, or rather you are not ready; but if you know my purpose you will realize the necessity for bending your energy to the consummation of my purpose, and to that end you will strive even more diligently than you have to perfect yourself in the high, scientific art I am imparting to you.

"I am a very old man," he continued after a brief pause, "even as age goes upon Barsoom. I have lived more than a thousand years. I have passed the allotted natural span of life, but I am not through with my life's work--I have but barely started it. I must not die. Barsoom must not be robbed of this wondrous brain and skill of mine. I have long had in mind a plan to thwart death, but it required another with skill equal to mine--two such might live for ever. I have selected you to be that other, for reasons that I already have explained--they are undefiled by sentimentalism. I did not choose you because I love you, or because I feel friendship for you, or because I think that you love me, or feel friendship towards me. I chose you because I knew that of all the inhabitants of a world you were the one least likely to fail me. For a time you will have my life in your hands. You will understand now why I have not been able to choose carelessly.

"This plan that I have chosen is simplicity itself provided that I can count upon just two essential factors--skill and self-interested loyalty in an assistant. My body is about worn out. I must have a new one. My laboratory is filled with wonderful bodies, young and complete with potential strength and health. I have but to select one of these and have my skilled assistant transfer my brain from this old carcass to the new one." He paused.

"I understand now, why you have trained me," I said. "It has puzzled me greatly."

"Thus and thus only may I continue my labors," he went on, "and thus may Barsoom be assured a continuance practically indefinitely, of the benefits that my brain may bestow upon her children. I may live for ever, provided I always have a skilled assistant, and I may assure myself of such by seeing to it that he never dies; when he wears out one organ, or his whole body, I can replace either from my great storehouse of perfect parts, and for me he can perform the same service. Thus may we continue to live indefinitely; for the brain, I believe, is almost deathless, unless injured or attacked by disease.

"You are not ready as yet to be entrusted with this important task. You must transfer many more brains and meet with and overcome the various irregularities and idiosyncrasies that constitute the never failing differences that render no two operations identical. When you gain sufficient proficiency I shall be the first to know it and then we shall lose no time in making Barsoom safe for posterity."

The old man was far from achieving hatred of himself. However, his plan was an excellent one, both for himself and for me. It assured us immortality--we might live for ever and always with strong, healthy, young bodies. The outlook was alluring--and what a wonderful position it placed me in. If the old man could be assured of my loyalty because of self-interest, similarly might I depend upon his loyalty; for he could not afford to antagonize the one creature in the world who could assure him immortality, or withhold it from him. For the first time since I had entered his establishment I felt safe.

As soon as I had left him I went directly to Valla Dia's apartment, for I wanted to tell her his wonderful news. In the weeks that had passed since her resurrection I had seen much of her and in our daily intercourse there had been revealed to me little by little the wondrous beauties of her soul, until at last I no longer saw the hideous, disfigured face of Xaxa when I looked upon her, but the eyes of my heart penetrated deeper to the loveliness that lay within that sweet mind. She had become my confidante, as I was hers, and this association constituted the one great pleasure of my existence upon Barsoom.

Her congratulations, when I told her of what had come to me, were very sincere and lovely. She said that she hoped I would use this great power of mine to do good in the world. I assured her that I would and that among the first things that I should demand of Ras Thavas was that he should give Valla Dia a beautiful body; but she shook her head.

"No, my friend," she said, "if I may not have my own body this old one of Xaxa's is quite as good for me as another. Without my own body I should not care to return to my native country; while were Ras Thavas to give me the beautiful body of another, I should always be in danger of the covetousness of his clients, any one of whom might see and desire to purchase it, leaving to me her old husk, conceivably one quite terribly diseased or maimed. No, my friend, I am satisfied with the body of Xaxa, unless I may again possess my own, for Xaxa at least bequeathed me a tough and healthy envelope, however ugly it may be; and for what do looks count here? You, alone, are my friend--that I have your friendship is enough. You admire me for what I am, not for what I look like, so let us leave well enough alone."

"If you could regain your own body and return to your native country, you would like that?" I demanded.

"Oh, do not say it!" she cried. "The simple thought of it drives me mad with longing. I must not harbour so hopeless a dream that at best may only tantalize me into greater abhorrence of my lot."

"Do not say that it is hopeless," I urged. "Death, only, renders hope futile."

"You mean to be kind," she said, "but you are only hurting me. There can be no hope."

"May I hope for you, then?" I asked. "For I surely see a way; however slight a possibility for success it may have, still, it is a way."

She shook her head. "There is no way," she said, with finality. "No more will Duhor know me."

"Duhor?" I repeated. "Your--someone you care for very much?"

"I care for Duhor very much," she answered with a smile, "but Duhor is not someone--Duhor is my home, the country of my ancestors."

"How came you to leave Duhor?" I asked. "You have never told me, Valla Dia."

"It was because of the ruthlessness of Jal Had, Prince of Amhor," she replied.

"Hereditary enemies were Duhor and Amhor; but Jal Had came disguised into the city of Duhor, having heard, they say, of the great beauty attributed to the only daughter of Kor San, Jeddak of Duhor, and when he had seen her he determined to possess her. Returning to Amhor he sent ambassadors to the court of Kor San to sue for the hand of the Princess of Duhor; but Kor San, who had no son, had determined to wed his daughter to one of his own Jeds, that the son of this union, with the blood of Kor San in his veins, might rule over the people of Duhor; and so the offer of Jal Had was declined.

"This so incensed the Amhorian that he equipped a great fleet and set forth to conquer Duhor and take by force that which he could not win by honorable methods. Duhor was, at that time, at war with Helium and all her forces were far afield in the south, with the exception of a small army that had been left behind to guard the city. Jal Had, therefore, could not have selected a more propitious time for an attack. Duhor fell, and while his troops were looting the fair city Jal Had, with a picked force, sacked the palace of the Jeddak and searched for the princess; but the princess had no mind to go back with him as Princess of Amhor. From the moment that the vanguard of the Amhorian fleet was seen in the sky she had known, with the others of the city, the purpose for which they came, and so she used her head to defeat that purpose.

"There was in her retinue a cosmetologist whose duty it was to preserve the lustrous beauty of the princess' hair and skin and prepare her for public audiences, for fetes and for the daily intercourse of the court. He was a master of his art; he could render the ugly pleasant to look upon, he could make the plain lovely, and he could make the lovely radiant. She called him quickly to her and commanded him to make the radiant ugly, and when he had done with her none might guess that she was the Princess of Duhor, so deftly had he wrought with his pigments and his tiny brushes.

"When Jal Had could not find the princess within the palace, and no amount of threat or torture could force a statement of her whereabouts from the loyal lips of her people, the Amhorian ordered that every woman within the palace be seized and taken to Amhor; there to be held as hostages until the Princess of Duhor should be delivered to him in marriage. We were, therefore, all seized and placed upon an Amhorian war ship which was sent back to Amhor ahead of the balance of the fleet, which remained to complete the sacking of Duhor.

"When the ship, with its small convoy, had covered some four thousand of the five thousand haads that separate Duhor from Amhor, it was sighted by a fleet from Phundahl which immediately attacked. The convoying ships were destroyed or driven off and that which carried us was captured. We were taken to Phundahl where we were put upon the auction block and I fell to the bid of one of Ras Thavas' agents. The rest you know."

"And what became of the princess?" I asked.

"Perhaps she died--her party was separated in Phundahl--but death could not more definitely prevent her return to Duhor. The Princess of Duhor will never again see her native country."

"But you may!" I cried, for I had suddenly hit upon a plan. "Where is Duhor?"

"You are going there?" she asked, laughingly.

"Yes!"

"You are mad, my friend," she said. "Duhor lies a full seven thousand, eight hundred haads from Toonol, upon the opposite side of the snow-clad Artolian Hills. You, a stranger and alone, could never reach it; for between lie the Toonolian Marshes, wild hordes, savage beasts and warlike cities. You would but die uselessly within the first dozen haads, even could you escape from the island upon which stands the laboratory of Ras Thavas; and what motive is there to prompt you to such a useless sacrifice?"

I could not tell her. I could not look upon that withered figure and into that hideous and disfigured face and say: "It is because I love you, Valla Dia." But that, alas, was my only reason. Gradually, as I had come to know her through the slow revealment of the wondrous beauty of her mind and soul, there had crept into my heart a knowledge of my love; and yet, explain it I cannot, I could not speak the words to that frightful old hag. I had seen the gorgeous mundane tabernacle that had housed the equally gorgeous spirit of the real Valla Dia--that I could love; her heart and soul and mind I could love; but I could not love the body of Xaxa. I was torn, too, by other emotions, induced by a great doubt--could Valla Dia return my love. Habilitated in the corpse of Xaxa, with no other suitor, nay, with no other friend she might, out of gratitude or through sheer loneliness, be attracted to me; but once again were she Valla Dia the beautiful and returned to the palace of her king, surrounded by the great nobles of Duhor, would she have either eyes or heart for a lone and friendless exile from another world? I doubted it--and yet that doubt did not deter me from my determination to carry out, as far as Fate would permit, the mad scheme that was revolving in my brain.

"You have not answered my question, Vad Varo," she interrupted my surging thoughts. "Why would you do this thing?"

"To right the wrong that has been done you, Valla Dia," I said.

She sighed. "Do not attempt it, please," she begged. "You would but rob me of my one friend, whose association is the only source of happiness remaining to me. I appreciate your generosity and your loyalty, even though I may not understand them; your unselfish desire to serve me at such suicidal risk touches me more deeply than I can reveal, adding still further to the debt I owe you; but you must not attempt it--you must not."

"If it troubles you, Valla Dia," I replied, "we will not speak of it again; but know always that it is never from my thoughts. Some day I shall find a way, even though the plan I now have fails me."

The days moved on and on, the gorgeous Martian nights, filled with her hurtling moons, followed one upon another. Ras Thavas spent more and more time in directing my work of brain transference. I had long since become an adept; and I realized that the time was rapidly approaching when Ras Thavas would feel that he could safely entrust to my hands and skill his life and future. He would be wholly within my power and he knew that I knew it. I could slay him; I could permit him to remain for ever in the preserving grip of his own anaesthetic; or I could play any trick upon him that I chose, even to giving him the body of a calot or a part of the brain of an ape; but he must take the chance and that I knew, for he was failing rapidly. Already almost stone blind, it was only the wonderful spectacles that he had himself invented that permitted him to see at all; long deaf, he used artificial means for hearing; and now his heart was showing symptoms of fatigue that he could not longer ignore.

One morning I was summoned to his sleeping apartment by a slave. I found the old surgeon lying, a shrunken, pitiful heap of withered skin and bones.

"We must hasten, Vad Varo," he said in a weak whisper. "My heart was like to have stopped a few tals ago. It was then that I sent for you." He pointed to a door leading from his chamber. "There," he said, "you will find the body I have chosen. There, in the private laboratory I long ago built for this very purpose, you will perform the greatest surgical operation that the universe has ever known, transferring its most perfect brain to the most beautiful and perfect body that ever has passed beneath these ancient eyes. You will find the head already prepared to receive my brain; the brain of the subject having been removed and destroyed--totally destroyed by fire. I could not possibly chance the existence of a brain desiring and scheming to regain its wondrous body. No, I destroyed it. Call slaves and have them bear my body to the ersite slab."

"That will not be necessary," I told him; and lifting his shrunken form in my arms as he had been an Earthly babe, I carried him into the adjoining room where I found a perfectly lighted and appointed laboratory containing two operating tables, one of which was occupied by the body of a red-man. Upon the surface of the other, which was vacant, I laid Ras Thavas, then I turned to look at the new envelope he had chosen. Never, I believe, had I beheld so perfect a form, so handsome a face--Ras Thavas had indeed chosen well for himself. Then I turned back to the old surgeon. Deftly, as he had taught me, I made the two incisions and attached the tubes. My finger rested upon the button that would start the motor pumping his blood from his veins and his marvellous preservative-anaesthetic into them. Then I spoke.

"Ras Thavas," I said, "you have long been training me to this end. I have labored assiduously to prepare myself that there might be no slightest cause for apprehension as to the outcome. You have, coincidentally, taught me that one's every act should be prompted by self-interest only. You are satisfied, therefore, that I am not doing this for you because I love you, or because I feel any friendship for you; but you think that you have offered me enough in placing before me a similar opportunity for immortality.

"Regardless of your teaching I am afraid that I am still somewhat of a sentimentalist I crave the redressing of wrongs. I crave friendship and love. The price you offer is not enough. Are you willing to pay more that this operation may be successfully concluded?"

He looked at me steadily for a long minute. "What do you want?" he asked. I could see that he was trembling with anger, but he did not raise his voice.

"Do you recall 4296-E-2631-H?" I inquired.

"The subject with the body of Xaxa? Yes, I recall the case. What of it?"

"I wish her body returned to her. That is the price you must pay for this operation."

He glared at me. "It is impossible. Xaxa has the body. Even if I cared to do so, I could never recover it. Proceed with the operation!"

"When you have promised me," I insisted.

"I cannot promise the impossible--I cannot obtain Xaxa. Ask me something else. I am not unwilling to grant any reasonable request."

"That is all I wish--just that; but I do not insist that you obtain the body. If I bring Xaxa here will you make the transfer?"

"It would mean war between Toonol and Phundahl," he fumed.

"That does not interest me," I said. "Quick! Reach a decision. In five tals I shall press this button. If you promise what I ask, you shall be restored with a new and beautiful body; if you refuse you shall lie here in the semblance of death for ever."

"I promise," he said slowly, "that when you bring the body of Xaxa to me I will transfer to that body any brain that you select from among my subjects."

"Good!" I exclaimed, and pressed the button.