"Well now, Dr. Sheffield, what is it?" said Cimon. The astrophysicist sat at his desk, on which papers and film formed rigidly arranged heaps about a small Macfreed integrator, and watched Sheffield step over the threshold.

Sheffield sat carelessly down upon the tautly yanked topsheet of Cimon's bunk. He was aware of Cimon's annoyed glance in that direction and it did not worry him. In fact, he rather enjoyed it.

He said, "I have a quarrel with your choice of men to go to the expedition site. It looks as though you've picked two men for the physical sciences and three for the biological sciences. Right?"

"Yes."

"I suppose you think you've covered the ground like a Danielski ovospore at perihelion."

"Oh, space! Have you anything to suggest?"

"I would like to come along myself."

"Why?"

"You have no one to take care of the mental sciences."

"The mental sciences! Good Galaxy! Dr. Sheffield, five men are quite enough to risk. As a matter of fact, Doctor, you and your-uh-ward were assigned to the scientific personnel of this ship by order of the Bureau of Outer Provinces without any prior consultation of myself. I'll be frank. If I had been consulted, I would have advised against you. I don't see the function of mental science in an investigation such as this, which, after all, is purely physical. It is too bad that the Bureau wishes to experiment with Mnemonics on an occasion such as this. We can't afford scenes like that one with Rodriguez."

Sheffield decided that Cimon did not know of Mark's connection with the original decision to send out the expedition.

He sat upright, hands on knees, elbows cocked outward, and let a freezing formality settle over him. "So you wonder about the function of mental science in an investigation such as this, Dr. Cimon. Suppose I told you that the end of the first settlement might possibly be explained on a simple, psychological basis."

"It wouldn't impress me. A psychologist is a man who can explain anything and prove nothing." Cimon smirked like a man who had made an epigram and was proud of it

Sheffield ignored it. He said, "Let me go into a little detail. In what way is Junior different from every one of the eightythree thousand inhabited worlds?"

"Our information is as yet incomplete. I cannot say."

"Oh, cobber-vitals. You had the necessary information before you ever came here. Junior has two suns."

"Well, of course." But the astrophysicist allowed a trace of discomfiture to enter his expression.

"Colored suns, mind you. Colored suns. Do you know what that means? It means that a human being, yourself or myself, standing in the full glare of the two suns, would cast two shadows. One blue green, one red orange. The length of each would naturally vary with the time of day. Have you taken the trouble to verify the color distribution in those shadows? The what-do-you-call-'em-reflection spectrum?"

"I presume," said Cimon loftily, "they'd be about the same as the radiation spectra of the suns. What are you getting at?"

"You should check. Wouldn't the air absorb some wave lengths? And the vegetation? What's left? And take Junior's moon, Sister. I've been watching it in the last few nights. It's in colors, too, and the colors change position."

"Well, of course, damn it. It runs through its phases independently with each sun."

"You haven't checked its reflection spectrum, either, have you?"

"We have that somewhere. There are no points of interest about it. Of what interest is it to you, anyway?"

"My dear Dr. Cimon, it is a well-established psychological fact that combinations of red and green colors exert a deleterious effect on mental stability. We have a case here where the red-green chromopsychic picture (to use a technical term) is inescapable and is presented under circumstances which seem most unnatural to the human mind. It is quite possible that chromopsychosis could reach the fatal level by inducing hypertrophy of the trinitarian follicles, with consequent cerebric catatonia."

Cimon looked floored. He said, "I never heard of such a thing."

"Naturally not," said Sheffield (it was his turn to be lofty). "You are not a psychologist. Surely you are not questioning my professional opinion."

"No, of course not. But it's quite plain from the last reports of the expedition that they were dying of something that sounded like a respiratory disease."

"Correct, but Rodriguez denies that and you accepted his professional opinion."

"I didn't say it was a respiratory disease. I said it sounded like one. Where does your red-green chromothingumbob come in?"

Sheffield shook his head. "You laymen have your misconceptions. Granted that there is a physical effect, it still does not imply that there may not be a mental cause. The most convincing point about my theory is that red-green chromopsychosis has been recorded to exhibit itself first as a psychogenic respiratory infection. I take it you are not acquainted with psycho-genics."

"No, It's out of my field."

"Well, yes. I should say so. Now my own calculations show me that under the heightened oxygen tension of this world, the psychogenic respiratory infection is both inevitable and particularly severe. For instance, you've observed the moon-Sister, I mean-in the last few nights."

"Yes, I have observed Ilium." Cimon did not forget Sister's official name even now.

"You watched it closely and over lengthy periods? Under magnification?"

"Yes." Cimon was growing uneasy.

"Ah," said Sheffield. "Now the moon colors in the last few nights have been particularly virulent. Surely you must be noticing just a small inflammation of the mucus membrane of the nose, a slight itching in the throat. Nothing painful yet, I imagine. Have you been coughing or sneezing? Is it a little hard to swallow?"

"I believe I-" Cimon swallowed, then drew in his breath sharply. He was testing.

Then he sprang to his feet, fists clenched and mouth working. "Great galaxy, Sheffield, you had no right to keep quiet about this. I can feel it now. What do I do, Sheffield? It's not incurable, is it? Damn it, Sheffield"-his voice went shrill- "why didn't you tell us this before?"

"Because," said Sheffield calmly, "there's not a word of truth in anything I've said. Not one word. There's no harm in colours. Sit down, Dr. Cimon. You're beginning to look foolish."

"You said," said Cimon, thoroughly confused, and in a voice that was beginning to strangle, "that it was your professional opinion that-"

"My professional opinion! Space and little comets, Cimon, what's so magic about a professional opinion? A man can be lying or he can just plain be ignorant, even about the final details of his own specialty. A professional can be wrong because he's ignorant of a neighboring specialty. He may be certain he's right and still be wrong.

"Look at you. You know all about what makes the Universe tick and I'm lost completely except that I know that a star is something that twinkles and a light-year is something that's long. And yet you'll swallow gibberish psychology that a freshman student of mentics would laugh his head off at. Don't you think, Cimon, it's time we worried less about professional opinion and more about over-all co-ordination?"

The color washed slowly out of Cimon's face. It turned waxy-pale. His lips trembled. He whispered, "You used professional status as a cloak to make a fool of me."

"That's about it," said Sheffield.

"I have never, never-" Cimon gasped and tried a new start. "I have never witnessed anything as cowardly and unethical."

"I was trying to make a point."

"Oh, you made it. You made it." Cimon was slowly recovering, his voice approaching normality. "You want me to take that boy of yours with us."

"That's right."

"No. No. Definitely no. It was no before you came in here and it's no a million times over now."

"What's your reason? I mean before I came in."

"He's psychotic. He can't be trusted with normal people."

Sheffield said grimly, "I'll thank you not to use the word, 'psychotic.' You are not competent to use it. If you're so precise in your feeling for professional ethics, remember to stay out of my specialty in my presence. Mark Annuncio is perfectly normal."

"After that scene with Rodriguez? Yes. Oh, yes."

"Mark had the right to- ask- his question. It was his job to do so and his duty. Rodriguez had no right to be boorish about it."

"I"ll have to consider Rodriguez first, if you don't mind."

"Why? Mark Annuncio knows more than Rodriguez. For that matter, he knows more than you or I. Are you trying to bring back an intelligent report or to satisfy a petty vanity?"

"Your statements about what your boy knows do not impress me. I am quite aware he is an efficient parrot. He understands nothing, however. It is my duty to see to it that data is made available to him because the Bureau has ordered that. They did not consult me, but very well. I will co-operate that far. He will receive his data here in the ship."

Sheffield said, "Not adequate, Cimon. He should be on the spot. He may see things our precious specialists will not."

Cimon said freezingly, "Very likely. The answer, Sheffield, is no. There is no argument that can possibly persuade me." The astrophysist's nose was pinched and white.

"Because I made a fool of you?"

"Because you violated the most fundamental obligation of a professional man. No respectable professional would ever use his specialty to prey on the innocence of a non-associate professional."

"So I made a fool of you."

Cimon turned away. "Please leave. There will be no further communication between us, outside the most necessary business, for the duration of the trip."

"If I go," said Sheffield, "the rest of the boys may get to hear about this."

Cimon started. "You're going to repeat our little affair?" A cold smile rested on his lips, then went its transient and contemptuous way. "You'll broadcast the dastard you were."

"Oh, I doubt they'll take it seriously. Everyone know psychologists will have their little jokes. Besides, they'll be so busy laughing at you. You know-the every impressive Dr. Cimon scared into a sore throat and howling for mercy after a few mystic words of gibberish."

"Who'd believe you?" cried Cimon.

Sheffield lifted his right hand. Between thumb and forefinger was a small rectangular object, studded with a line of control toggles.

"Pocket recorder," he said. He touched one of the toggles and Cimon's voice was suddenly saying, "Well, now, Dr. Sheffield, what is it?"

It sounded pompous, peremptory, and even a little smug.

"Give me that!" Cimon hurled himself at the lanky psychologist.

Sheffield held him off. "Don't try force, Cimon. I was in amateur wrestling not too long ago. Look, I"ll make a deal with you."

Cimon was still writhing toward him, dignity forgotten, panting his fury. Sheffield kept him at arm's length, backing slowly.

Sheffield said, "Let Mark and myself come along and no one will ever see or hear this."

Slowly Cimon simmered down. He gasped, "Will you let me have it, then?"

"After Mark and I are out at the settlement site."

"I'm to trust you." He seemed to take pains to make that as offensive as possible.

"Why not? You can certainly trust me to broadcast this if you don't agree. I'll play it off for Vernadsky first. He'll love it. You know his corny sense of humor."

Cimon said in a voice so low it could hardly be heard, "You and the boy can come along." Then vigorously, "But remember this, Sheffield. When we get back to Earth, I"ll have you before the Central Committee of the G.A.A.S. That's a promise. You'll be de-professionalized."

Sheffield said, "I'm not afraid of the Galactic Association for the Advancement of Science." He let the syllables resound. "After all, what will you accuse me of? Are you going to play this recording before the Central Committee as evidence? Come, come, let's be friendly about this. You don't want to broadcast your own-uh-mistake before the primest stuffed shirts in eighty-three thousand worlds."

Smiling gently, he backed out the door.

But when he closed the door between himself and Cimon, his smile vanished. He hadn't liked to do this. Now that he had done it, he wondered if it were worth the enemy he had made.