For those unfamiliar with the story, Malancandra is Lewis' vision of an unfallen, Edenic planet Mars where several races of rational creatures exist in harmony under the rule of an angelic being called Oyarsa. Weston and Devine are humans bent on using Malacandra for their own purposes, and Ransom - the protagonist - is taken to the planet against his will to help them achieve their ends.
Devine's interest in Malacandra is simply profit (it's loaded with gold), but Weston is driven by loftier ideals. Knowing that Earth can only sustain humanity for a limited period of time, Weston sees Malacandra as an opportunity to extend the human genetic line indefinitely. This is his summum bonum, and he is committed to it even if it means the devastation and eventual extinction of the Malacandrians.
