CLOSE TO CRITICAL

with a single exploring machine. Had that been the actual plan, of course it would have been ridiculous; but the men had something else in mind. One machine is not much; a machine with a crew of assistants, particularly if the crew is part of a more or less world-wide culture, is something very different. The operators very definitely hoped to find local help—in spite of the rather extreme environment into which their machine had fallen. They were experienced men, and knew something of the ways of life in the universe.

However, weeks went by, and then months, with no sign .of a creature possessing more than the rudiments of a nervous system. Had the men understood the operation of the lensless, many-spined "eyes" of the local animals they might have been more hopeful; but as it was most of them grew resigned to facing a job of several lifetimes. It was sheer chance that when a thinking creature finally did turn up it was discovered by the robot. Had it been the other way around—if the native had discovered the machine—history could easily have been very different on several planets.

The creature, when they did see it, was big. It towered fully nine feet in height, and on that planet must have weighed well over a ton. It conformed to the local custom as regarded scales and number of limbs, but it walked erect on two* of the appendages, seemed not to be using the next two, and used the upper four for prehension. That was the fact that betrayed its intelligence; two long and two shorter spears, each with a carefully chipped stone head, were being carried hi obvious readiness for instant use.

Perhaps the stone disappointed the human watchers, or perhaps they remembered what happened to metals on this planet and refrained from jumping to conclusions about the culture level suggested by the material.

In any case, they watched the native carefully.

This was easier than it might have been; the present

Prologue: Investigation; Annexation 13

neighborhood, many miles from the original landing point, was a good deal rougher in its contours. The vegetation was both higher and somewhat less brittle, though it was still virtually impossible to avoid leaving a trail where the robot crawled. The men guessed at first that the higher plants had prevented the native from seeing the relatively small machine; then it became apparent that the creature's attention was fully occupied by something else.

It was traveling slowly and apparently trying to leave as little trail as possible. It was also making allowance for the fact that to leave no trail was not practicable; periodically it stopped and built a peculiar arrangement consisting of branches from some of the rarer, springy plants and the sharp stone blades which it took hi seemingly endless supply from a large leather sack slung about its scaly body.

The nature of these arrangements was clear, after the native had gotten far enough ahead to permit a close inspection. They were booby traps, designed to drive a stone point into the body of anything attempting to follow hi the creature's footsteps. They must have been intended against animals rather than other natives, since they could easily be avoided merely by paralleling the trail instead of following it.

The fact that the precaution was being taken at all, however, made the whole situation extremely interesting, and the robot was made to follow with all possible caution. The native traveled five or six miles in this fashion, and during this time set about forty of the traps. The robot avoided these without trouble, but several times tripped others which had apparently been set earlier. The blades did no harm to the machine; some of them actually broke against the plastic. It began to look as though the whole neighborhood had been "mined," however.

Eventually the trail led to a rounded hill. The native

14