 Why does Thig leave a note at Torp's desk?
Thig carefully smoothed the dark sand and seaweed of the lonely beach over the metal lid of the flexible ringed tunnel that linked the grubby ship from another planet with the upper air. Oddest of all, he wore no garments, other than the necessary belt and straps to support his rod-like weapon of white metal and his pouches for food and specimens. Here he patiently sat down to wait for an Earthman or an Earthwoman to pass. His task now was to bring a native, intact if possible, back to the carefully buried space cruiser where his two fellows and himself would drain the creature's mentality of all its knowledge. Feebly he had punched a key two days ago and a $ sign had appeared. "There it is," announced Thig, dropping the limp body of the captured Earthman to the metal deck-plates. "Thig will be this creature!" announced Torp. "With a psychic relay we will transfer the Earthman's memories and meager store of knowledge to the brain of Thig! "For the good of the Horde," Thig intoned almost piously as he lifted Terry's body and headed for the laboratory. So it was that the bodies of the Earthman and the Orthan were strapped on two parallel tables of chill metal and the twin helmets, linked to one another by the intricacies of the psychic relay, put upon their heads. Twice, with subtle drugs they restored pseudo-life to his body and kept the electrical impulses throbbing from his tortured brain, but after the third suspension of life Thig removed his helmet.
 He wants to make sure no one comes to invade Earth, and have reason to fear doing so.
 He wants to make sure no one comes to invade Earth, and have reason to fear doing so.  He wants to warn the other Orthans about the potential dangers of Earth.  He wants someone to understand what had happened.  He feels badly about killing Kam and Torp, and wants to leave a final message on their behalf.