Weston kills several natives of the new planet that he explores. He does so out of indifference and arrogance, but he primarily does so out of fear. Weston fears the creatures themselves but the unknown even more. He does not understand the creatures, their culture, their language, or anything about their planet. Being a man of great intelligence and understanding, he greatly fears what he is incapable of understanding. Through this fear, he kills many of the planet's inhabitants.

Weston also fears the extinction of the human race. While his own death is inevitable, Weston hopes to colonize the new planet in order to continue the human race indefinitely. While the natives of the planet are not human, they are certainly as intelligent as humans, if not more so. However, Weston is unable to accept this fact, perhaps fearing inferiority, and expresses the belief that humans have the inherent right to conquer the planet and persevere into the future.

Out of the Silent Planet is the first of what is known as The Space Trilogy or The CosmicTrilogy.  Dr. Weston and Dick Devine are travelers to the planet Malacandra.  

Though Dr. Weston is somewhat barbaric and aggressive, he fears the seroni. The seroni, or sorns, are humanoids with a highly developed sense of the scientific and technical aspects of life.  He fears them so much that he is willing to bring them a human sacrifice - Dr. Elwin Ransom.

Weston also fears the primitive inhabitants of Malacandra.  His speech, in chapter 20, is a manifestation of that fear.  He denounces their primitive ways as a reason to seek their annihilation.  Rather than admit his own primitive ancestry, and allow the beings of Malacandra to develop, he sees it as his mission to "cleanse" the planet.