That power corrupts is an inevitable conclusion of Animal Farm. When the pigs take over they claim that their goal is to preside over a farm of equal animals, all working together to support one another. Yet power quickly proves to be too much for a pig. Small privileges quickly bloom into full-scale corruption, and the pigs begin more and more to resemble those whom they claim to replace.
Although their corruption worsens as the story progresses, the pigs are greedy from the start.
The transition in control from Snowball to Napoleon is the turning point for Animal Farm, representing the corruption of the race of pigs from sound leadership to corrupt dictatorship.