"Don't accuse us of ingratitude," cried Garth Jan vehemently. According to the Martian code of ethics, ingratitude was the supreme vice, and at the insinuation of that Garth's caution left him. "We never act without reason, we Martians. And certainly it is not for our own sake that we hide this magnificent ability."

The Earthman smiled mockingly. He was on the trail of something-he felt it in his bones-and the only way to get it out was to tease it out.

"No doubt there is some nobility behind it all. It is a strange attribute of your race that you can always find some altruistic motive for your actions."

GARTH JAN bit his lip angrily "You have no right to say that." For a moment he thought of pleading worry over Fields' future peace of mind as a reason for silence, but the latter's mocking reference to "altruism" had rendered that impossible. A feeling of anger crept over him gradually and that forced him to his decision.

There was no mistaking the note of frigid unfriendliness that entered his voice.

"I'll explain by analogy." The Martian stared straight ahead of him as he spoke, eyes half-closed.

"You have told me that I live in a world that is composed merely of shades of light and dark. You try to describe a world of your own composed of infinite variety and beauty. I listen but care little concerning it. I have never known it and never can know it. One does not weep over the loss of what one has never owned.

"But-what if you were able to give me the ability to see color for five minutes? What if, for five minutes, I reveled in wonders undreamed of? What if, after those five minutes, I have to return it forever? Would those five minutes of paradise be worth a lifetime of regret afterwards-a lifetime of dissatisfaction because of my own shortcomings? Would it not have been the kinder act never to have told me of color in the first place and so have removed its ever-present temptation?"

Fields had risen to his feet during the last part of the Martian's speech and his eyes opened wide in a wild surmise. "Do you mean an Earthman can possess the Martian sense if so desired?"

"For five minutes in a lifetime," Garth Jan's eyes grew dreamy, "and in those flve minutes sense-"

He came to a confused halt and glared angrily at his companion, "You know more than is good for you. See that you don't forget your promise."

He rose hastily and hobbled away as quickly as he could, leaning heavily upon the cane. Lincoln Fields made no move to stop him. He merely sat there and thought.

THE GREAT height of the cavern shrouded the roof in misty obscurity in which, at fixed intervals, there floated luminescent globes of radite. The air, heated by this subterranean volcanic stratum, wafted past gently. Before Lincoln Fields stretched the wide, paved avenue of the principal city of Mars, fading away into the distance.

He clumped awkwardly up to the entrance of the home of Garth Jan, the six-inch-thick layer of lead attached to each shoe a nuisance unending. Though it was still better than the uncontrollable bounding Earth muscles brought about in this lighter gravity.

The Martian was surprised to see his friend of six months ago but not altogether joyful. Fields was not slow to notice this but he merely smiled to himself. The opening formalities passed, the conventional remarks were made, and the two seated themselves.

Fields crushed the cigarette in the ash-tray and sat upright suddenly serious.

"I've come to ask for those five minutes you claim you can give me! May I have them?"

"Is that a rhetorical question? It certainly doesn't seem to require an answer."

Garth's tone was openly contemptuous.

The Earthman considered the other thoughtfully. "Do you mind if I outline my position in a few words?"

The Martian smiled indifferently. "It won't make any difference," he said.

"I'll take my chance on that. The situation is this: I've been born and reared in the lap of luxury and have been most disgustingly spoiled. I've never yet had a reasonable desire that I have not been able to fulfill, and I don't know what it means not to get what I want. Do you see?"

There was no answer and he continued, "I have found my happinese in beautiful sights, beautiful words, and beautiful sounds. I have made a cult of beauty. In a word, I am an aesthete."

"Most interesting," the Martian's stony expression did not change a whit, "but what bearing has all this on the problem at hand?"

"Just this: You speak of a new form of beauty-a form unknown to me at present and entirely inconceivable even, but one which could be known if you so wished.

The notion attracts me. It more than attracts me-it makes its demands of me.

Again I remind you that when a notion begins to make demands of me, I yield-I always have."

"You are not the master in this case," reminded Garth Jan. "It is crude of me to remind you of this, but you cannot force me, you know. Your words, in fact, are almost offensive in their implications."

"I am glad you said that, for it allows me to be crude in my turn without offending my conscience."

Garth Jan's only reply to this was a self-confident grimace.

"I make my demand of you," said Fields, slowly, "in the name of gratitude."

"Gratitude?" the Martian started violently.

Fieids grinned broadly, "It's an appeal no honorable Martian can refuse-by your own ethics. You owe me gratitude, now, because it was through me you gained entrance into the houses of the greatest and most honorable men of Earth."

"I know that," Garth Jan flushed angrily. "You are impolite to remind me of it."

"I have no choice. You acknowledged the gratitude you owe me in actual words, back on Earth. I demand the chance to possess this mysterious sense you keep so secret-in the name of this acknowledged gratitude. Can you refuse now?"

"You know I can't," was the gloomy response. "I hesitated only for your own sake."

The Martian rose and held out his hand gravely, "You have me by the neck, Lincoln. It is done. Afterwards, though, I owe you nothing more. This will pay my debt of gratitude. Agreed?"

"Agreed!" The two shook hands and Lincoln Fields continued in an entirely different tone. "We're still friends, though, aren't we? This little altercation won't spoil things?"

"I hope not. Come! Join me at the evening meal and we can discuss the time and place of your-er-five minutes."

Lincoln Fields tried hard to down the faint nervousness that filled him as he waited in Garth Jan's private "concert"-room. He felt a sudden desire to laugh as the thought came to him that he felt exactly as he usually did in a dentist's waiting room.

He lit his tenth cigarette, puffed twice and threw it away, "You're doing this very elaborately, Garth."

The Martian shrugged, "You have only five minutes so I might as well see to it that they are put to the best possible use. You're going to 'hear' part of a portwem which is to our sense what a great symphony (is that the word?) is to sound."

"Have we much longer to wait? The suspense, to be trite, is terrible."

"We're waiting for Novi Lon, who is to play the portwem, and for Done Vol, my private physician. They'll be along soon."

Fields wandered on to the low dais that occupied the center of the room and regarded the intricate mechanism thereupon with curious interest. The fore-part was encased in gleaming aluminum leaving exposed only seven tiers of shining black knobs above and five large white pedals below. Behind, however, it lay open and within there ran crossings and recrossings of fine wires in incredibly complicated paths.

"A curious thing, this," remarked the Earthman.

The Martian joined him on the dais, "It's an expensive instrument. It cost me ten thousand Martian credits."

"How does it work?"

"Not so differently from a Terrestrial piano. Each of the upper knobs controls a different electric circuit. Singly and together an expert portwem player could, by manipulating the knobs, form any conceivable pattern of electric current. The pedals below control the strength of the current."