Night settles in time on all habitable planets. Not always, perhaps, at respectable intervals, since recorded periods of rotation vary from fifteen to fifty-two hours. That fact requires the most strenuous psychological adjustment from those traveling from planet to planet.

On many planets such adjustments are made, and the waking-sleeping periods are tailored to fit. On many more the almost universal use of conditioned atmospheres and artificial lighting make the day-night question secondary except in so far as it modifies agriculture. On a few planets (those of the extremes) arbitrary divisions are made which ignore the trivial facts of light and dark.

But always, whatever the social conventions, the coming of night has a deep and abiding psychological significance, dating back to man's pre-human arboreal existence. Night will always be a time of fear and insecurity, and the heart will sink with the sun.

Inside Palace Central there was no sensory mechanism by which one could tell the coming of night, yet Biron felt that coming through some indefinite instinct hidden in the unknown corridors of the human brain. He knew that outdoors the night's blackness was scarcely relieved by the futile sparks of the stars. He knew that, if it were the right time of year, the jagged "hole in space" known as the Horsehead Nebula (so familiar to all the Trans-Nebular Kingdoms) inked out half the stars that might otherwise have been visible.

And he was depressed again. He had not seen Artemisia since the little talk with the Director, and he found himself resenting that. He had looked forward to dinner; he might have spoken to her. Instead, he had eaten alone, with two guards lounging discontentedly just outside the door. Even Gillbret had left him, presumably to eat a less lonely meal in the company one would expect in a palace of the Hinriads.

So that when Gillbret returned and said, "Artemisia and I have been discussing you," he obtained a prompt and interested reaction.

It merely amused him and he said so. "First I want to show you my laboratory," he had said then. He gestured and the two guards moved off.

"What kind of a laboratory?" asked Biron with a definite loss of interest.

"I build gadgets," was the vague response.

It was not a laboratory to the eye. It was more nearly a library, with an ornate desk in the corner.

Biron looked it over slowly. "And you build gadgets here? What kind of gadgets?"

"Well, special sounding devices to spy out the Tyrannian spy beams in a brand-new way. Nothing they can detect. That's how I found out about you, when the first word came through from Aratap. And I have other amusing trinkets. My visisonor, for instance. Do you like music?"

"Some kinds."

"Good. I invented an instrument, only I don't know if you can properly call it music." A shelf of book films slid out and aside at a touch. "This is not really much of a hiding place, but nobody takes me seriously, so they don't look. Amusing, don't you think? But I forget, you're the unamused one."

It was a clumsy, boxlike affair, with that singular lack of gloss and polish that marks the homemade object. One side of it was studded with little gleaming knobs. He put it down with that side upward.

"It isn't pretty," Gillbret said, "but who in Time cares? Put the lights out. No, no! No switches or contacts. Just wish the lights were out. Wish hard! Decide you want them out."

And the lights dimmed, with the exception of the faint pearly luster of the ceiling that made them two ghostly faces in the dark. Gillbret laughed lightly at Biron's exclamation.

"Just one of the tricks of my visisonor. It's keyed to the mind like personal capsules are. Do you know what I mean?"

"No, I don't, if you want a plain answer."

"Well," he said, "look at it this way. The electric field of your brain cells sets up an induced one in the instrument. Mathematically, it's fairly simple, but as far as I know, no one has ever jammed all the necessary circuits into a box this size before. Usually, it takes a five-story generating plant to do it. It works the other way too. I can close circuits here and impress them directly upon your brain, so that you'll see and hear without any intervention of eyes and ears. Watch!"

There was nothing to watch, at first. And then something fuzzy scratched faintly at the corner of Biron's eyes. It became a faint blue-violet ball hovering in mid-air. It followed him as he turned away, remained unchanged when he closed his eyes. And a clear, musical tone accompanied it, was part of it, was it.

It was growing and expanding and Biron became disturbingly aware that it existed inside his skull. It wasn't really a color, but rather a colored sound, though without noise. It was tactile, yet without feeling.

It spun and took on an iridescence while the musical tone rose in pitch till it hovered above him like falling silk. Then it exploded so that gouts of color splattered at him in touches that burned momentarily and left no pain.

Bubbles of rain-drenched green rose again with a quiet, soft moaning. Biron thrust at them in confusion and became aware that he could not see his hands nor feel them move. There was nothing, only the little bubbles filling his mind to the exclusion of all else.

He cried out soundlessly and the fantasy ceased. Gillbret was standing before him once again in a lighted room, laughing. Biron felt an acute dizziness and wiped shakily at a chilled, moist forehead. He sat down abruptly.

"What happened?" he demanded, in as stiff a tone as he could manage.

Gillbret said, "I don't know. I stayed out of it. You don't understand? It was something your brain had lacked previous experience with. Your brain was sensing directly and it had no method of interpretation for such a phenomenon. So as long as you concentrated Qn the sensation, your brain could only attempt, futilely, to force the effect into the old, familiar pathways. It attempts separately and simultaneously to interpret it as sight and sound and touch. Were you conscious of an odor, by the way? Sometimes it seemed to me that I smelled the stuff. With dogs I imagine the sensation would be forced almost entirely into odor. I'd like to try it on animals someday.

"On the other hand, if you ignore it, make no attack upon it, it fades away. It's what I do, when I want to observe its effects on others, and it isn't difficult."

He placed a little veined hand upon the instrument, fingering the knobs aimlessly. "Sometimes I think that if one could really study this thing, one could compose symphonies in a new medium; do things one could never do with simple sound or sight. I lack the capacit,y for it, I'm afraid."

Biron said abruptly, "I'd like to ask you a question."

"By all means."

"Why don't you put your scientific ability to worth-while use instead of-"

"Wasting it on useless toys? I don't know. It may not be entirely useless. This is against the law, you know."

"What is?"

"The visisonor. Also my spy devices. If the Tyranni knew, it could easily mean a death sentence."

"Surely, you're joking."

"Not at all. It is obvious that you were brought up on a cattle ranch. The young people cannot remember what it was like in the old days, I see." Suddenly his head was to one side and his eyes were narrowed to slits. He asked, "Are you opposed to Tyrannian rule? Speak freely. I tell you frankly that I am. I tell you also that your father was."

Biron said calmly, "Yes, I am."

"Why?"

"They are strangers, outlanders. What right have they to rule in Nephelos or in Rhodia?"

"Have you always thought that?" Biron did not answer.

Gillbret sniffed. "In other words, you decided they were strangers and outlanders only after they executed your father, which, after all, was their simple right. Oh, look, don't fire up. Consider it reasonably. Believe me, I'm on your side. But think! Your father was Rancher. What rights did his herdsmen have? If one of them had stolen cattle for his own use or to sell to others, what would have been his punishment? Imprisonment as a thief. If he had plotted the death of your father, for whatever reason, for perhaps a worthy reason in his own eyes, what would have been the result? Execution, undoubtedly. And what right has your father to make laws and visit punishment upon his fellow human beings? H e was their Tyranni.