Robin got to his feet, went to it. Something had come into the cave silently, had taken the sack, and had examined its contents. He looked about, amazed and wondering.
Now he saw that other things had been touched. His canteen had been rolled over and the stopper unplugged. The water that had been inside was a little puddle on the cave floor.
Alarmed, Robin strung his bow, notched an arrow, and looked carefully around at the surrounding vegetation. Something was there, something big and cunning.
His eyes searched the ground and then he saw an outline in water from the canteen. Whatever it was had stepped into the puddle and then walked out of the cave. Robin saw a series of footprints.
Something that walked on two legs, something that took steps with a man-sized stride, something with three toes on each foot, that walked upright, was able to open bottles, look into sacks, and spy on sleeping strangers.
Something that might well be to the Moontiger and the Moonhound what Earth man was to the Earth tiger and the Earth hound. Moonman!
[11. The Glass Man]
The situation was so astonishing that for a while Robin did not do anything but sit down inside his cave and catch his breath. Somehow he had assumed all along that he would not find anything on a human scale on the Moon. His life had been mainly confined to the first cavern-bubble he'd arrived at and this, as he now realized, had been a rather isolated one.
Unconsciously, he had assumed that life in other protected airtight sublunar areas would be on a similarly low and limited level. Now he realized that he had had no right to make such an assumption. The Moon might harbor thousands and tens of thousands of bubbles; some might be hundreds of miles in scale; some, lower down, nearer the still-warm volcanic heart of the satellite, might even approach tropical climates and show little of the semi-monthly seasonal changes. In such places life might grow in profusion, might compel the kind of battle for existence as would bring out the evolution of a brain-carrying creature living on its wits.