system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Trek Original Series Episode 1] If the aliens controlled everything the captain saw, heard, and felt, and their goal was to make him breed with the woman, why not just make him feel unbearably horny?
gpt
Doylist note: >!I assume by "Episode 1" you mean "The Cage". This was not in fact Episode 1, but the first pilot, which  was rejected by the network and never aired as originally edited. Material from this was later edited into the 2-part episode "The Menagerie". The pilot the network eventually accepted was "Where No Man Has Gone Before", which ultimately aired as Episode 3. "The Man Trap" aired as Episode 1, but was actually the 6th filmed. The first regular episode filmed after the series was green-lit was "The Corbomite Maneuver"; this aired as Episode 10.!<

They created illusions, and had no mental powers over reality. This meant they could alter a target's sensory perceptions, but could not make any actual alterations to his body. Thus, when Pike is choking one of the aliens who then threatens to destroy the Enterprise, Vina assures him they'd do it by their powers of illusion, making the crew operate controls in such a way as to wreck the ship. They couldn't do it directly by, say, mentally destabilizing the warp core.

Horniness is a hormonal condition, and they couldn't directly affect Pike's hormones. So they had to make him horny indirectly, by putting him and Vina in scenarios they thought might appeal to him.