The twenty-five or thirty human midgets who were moving in all directions across the field, between machines that seemed too formidable to be trusted had the brittle, sheen-bright look of figures cut out of isinglass.

Another illusion, of course. There had to be shadows, because there was nothing on Mars that could have brought about that big a change in the laws of optics. But by the same token the length and density of shadows can be altered a bit by atmospheric conditions, making light interception turn playful. So I didn't strain my eyes searching for deep purple halos around the human midges.

My only immediate concern was to reassure Joan in a calm and forceful way and escort her safely down to ground level, without letting her suspect that I shared her misgivings as to the stability of the spiral.

It was ridiculous on the face of it. But, as I've said, you can't argue with a feeling that whispers that your remote, dawn age ancestors must have felt the same way when they climbed out on a limb overhanging a precipice, and felt the whole tree begin to sway and shake beneath them.

"Hold tight to the rail and don't look down," I cautioned. "There's no real danger ... because a first-rate welding job was done on this structure. Barring an earthquake, it should be just as safe a century from now."

I shot a quick, concerned glance at her along with the warning. I guess I must have thought she'd be more shaken than she was, for she smiled when she saw the look of surprise in my eyes. It took me half a minute to realize that my guess as to how she'd be taking it hadn't gone so wide of the mark. Her pallor gave her away.

"A century would be much too long to wait," she breathed. "Another five minutes would be too long. If it's going to collapse, I'd rather find out right now."

I nodded and we started down. Several other passengers had emerged from the port and were looking up at the sky or downward as I'd done. Three men and a woman had emerged ahead of us and were almost at the base of the spiral. So far nothing had happened to them.

I've often toyed with the thought that there may be windows in the mind we can see out of sometimes—at oblique angles and around corners and without turning our heads. I could visualize the passengers who were descending behind us more clearly than you usually can in a mind's eye picture. Each face was in sharp focus and there was no blurring of their images as they moved. It was as if I was staring straight up at them through a crystal-clear pane of glass.

In that astonishingly bright inner vision—why look up and back when I did not doubt its accuracy?—Commander Littlefield was wasting no time in setting a good example. He'd descended the spiral so many times that great height meant nothing to him. He'd be ascending and descending at least ten more times just in the next few hours. But this was his big moment. I could already picture him striding across the disembarkation section to the Administration Unit with his shoulders held straight, and announcing officially, with a ring of pride in his voice, that the trip had been completed in record time, and the rocket had been berthed successfully. He was descending now with a confident smile on his lips, his Mars' legs buoyantly supporting him.