Animal farm symbolizes Russia and its Communist revolution. But a peculiar strenght of the book is that it represents all ideologies, be it socialist, liberal, capatalist, religious or otherwise. The power lies in showing that no matter in what ideology mankind believes (and Lenin really believed in his), we always end up in abusing the power we obtained. The analogy of the book is clear: the animals (working class people) remove the repressor, man, and by doing so ultimately fall for the same wealth & power that they once wanted to divide equally among the animals.
