George Orwell's Animal Farm is a sophisticated allegorical treatment of the failure of the Soviet experiment, an examination of how noble political philosophies can be exploited by power-hungry opportunists and perverted into tyranny. Orwell was a democratic socialist (maybe you've heard that phrase before), and lamented the Stalinist bastardization of socialist theory into an elitist reign of terror. The underlying theme of this tale isn't that socialism sucks - it's that it's hard, and that it's vulnerable to those who would twist it to their own ends.
When the Old Boar dies (Lenin, in most interpretations), the young pigs Napoleon and Snowball assume control of the revolution that wrested control of the farm from the human owner Jones (the Tsar). Napoleon is usually viewed as Stalin, while Snowball is an amalgam of Lenin and Trotsky. Napoleon seeks to bend the revolution to his own venal ambitions, while Snowball is more intent on honoring the fundamental tenets of Animalism, including peace, equality, and rejection of the indulgent decadence of humans. When Jones tries to reclaim his farm, it is Snowball who courageously leads the resistance, while Napoleon hides and plots.
Snowball is charismatic, intelligent, and rational, the best of the pigs, overcoming his baser instincts to push for better lives for his fellow animals. This, of course, is an obstacle to Napoleon's thirst for power (and its trappings), and so he conspires with his flunky Squealer to destroy Snowball's reputation and standing through lies and propaganda. A whisper campaign erodes Snowball's image from hero to villain, and he proves unable to fight back against Napoleon's secret police dogs and lack of scruple. Snowball's exile is the tipping point for the farm, when the noble experiment in self-rule and shared prosperity begins to devolve into dictatorship. The commandments of Animalism are adjusted to reflect Napoleon's desires, allowing him to wear clothes, drink booze, and sleep in beds, all marks of human behavior that the original revolution fought against. The pigs become a ruling class where none was envisioned.
While Animal Farm is a blisteringly accurate and detailed allegory for the first half-century of Soviet history, it also bears stern warnings for our own times. When a blustering, ambitious pig sets himself and his cronies above everyone else and tries to sell you on the fairy tale that it's for your own good, when he traffics in insidious falsehoods to tear down all rivals, and when he tells you you need to work harder to sustain his way of life, when he relies on a cult of personality to buttress his exploitation, watch out. I get the feeling we exiled Snowball a long time ago, and have become willing, even eager stooges of Napoleon.