The pigs' adoption of a human lifestyle represents the final, irrevocable betrayal of the principles Old Major had laid down on the night of the Rebellion. In his founding speech, he had commanded that no animal should ever live in a house, sleep in a bed, wear clothes, drink alcohol, smoke tobacco, touch money, or engage in trade, and that above all no animal must tyrannise over his own kind. The very first act of the liberated animals, after expelling Mr. Jones, was to fling into a fire the whips, bits, nose-rings, and other degrading human implements—a ritual of purification that seemed to seal the break with the old regime. Yet by the closing chapters of the story, the pigs have not only violated every one of these prohibitions but have come to embody the very human vices they were sworn to reject. The transformation is total: the pigs now supervise the other animals carrying whips in their trotters, buy themselves a wireless set, arrange to install a telephone, and take out subscriptions to John Bull, Tit-Bits, and the Daily Mirror. Napoleon himself strolls in the farmhouse garden with a pipe in his mouth, and the pigs take Mr. Jones's clothes out of the wardrobes and put them on—Napoleon appearing in a black coat, ratcatcher breeches, and leather leggings, while his favourite sow wears the watered silk dress Mrs. Jones had once worn on Sundays. The pigs have even learned to walk on their hind legs: Squealer, awkward but balanced, leads the way across the yard, and a long file of pigs follows, Napoleon himself emerging majestically upright, casting haughty glances from side to side, with his dogs gambolling round him.

This physical and behavioural metamorphosis is not merely cosmetic; it is the visible sign of a wholesale reversal of the revolution's aims. The pigs now wield the very instruments of oppression they had destroyed: whips, clothes, money, and the authority of humans. The sheep, who had once bleated "Four legs good, two legs bad" as a mantra of Animalism, are taught a new slogan—"Four legs good, two legs better"—to justify the pigs' upright posture. The farm has grown richer, but the wealth flows only to the pigs and the dogs. The other animals remain hungry, cold, and overworked, labouring longer hours than under Jones while Squealer reads out figures proving that production has increased by hundreds of percent. The animals cannot remember the old days clearly enough to compare; they have only Squealer's lists and the fading memory of the Rebellion. The pigs, meanwhile, devote themselves to mysterious paperwork—files, reports, minutes, memoranda—which they cover with writing and then burn in the furnace, a procedure Squealer insists is of the highest importance. The farmhouse, which had been preserved as a museum no animal might enter, is now the pigs' residence, and they sleep in beds with blankets, drink beer, and Napoleon receives half a gallon daily in the Crown Derby soup tureen. The terror that began with the expulsion of Snowball and the execution of confessing animals has become institutionalised: the nine dogs, raised in secret, now serve as Napoleon's bodyguard and enforcer, snarling at any animal that comes too close. The pigs have even renamed the farm back to "The Manor Farm," buried the skull of Old Major, removed the hoof and horn from the green flag, and suppressed the word "Comrade."

The climax of this transformation occurs when a delegation of neighbouring farmers, invited to tour the farm, joins the pigs for a banquet in the farmhouse. Mr. Pilkington of Foxwood toasts the prosperity of "The Manor Farm," and Napoleon replies by renaming the farm altogether. As the animals outside peer through the window, they see the pigs and the farmers playing cards, drinking, and laughing. A quarrel erupts over aces of spades, and the twelve voices shouting in anger are all alike. The creatures outside look from pig to man, and from man to pig, and from pig to man again; but already it is impossible to say which is which. The revolution has completed its cycle: the pigs have become the very thing they rose against, and the face of tyranny has merely changed from human to porcine, then become indistinguishable. The hopes of the animals—the golden future time sung in Beasts of England, the society of equals where no animal tyrannises over his own kind—have been dissolved into a new order that replicates the old one in every detail. What had begun as a rebellion against the injustice of Man ends with the pigs adopting not only his vices but his entire way of life, leaving the other animals still labouring, still hungry, and still unfree.