The morning after the Rebellion, the pigs revealed that during the previous three months they had taught themselves to read and write from an old spelling book discarded on the rubbish heap. Napoleon sent for pots of black and white paint, and Snowball, the best writer, painted out "Manor Farm" from the top bar of the five-barred gate and replaced it with "Animal Farm." This renaming was the first public act of the new regime. The pigs then set a ladder against the end wall of the big barn, where Snowball, with Squealer holding the paint-pot, climbed up to inscribe the Seven Commandments—principles derived from Old Major's speech—in great white letters that could be read thirty yards away. The commandments prohibited living in a house, sleeping in a bed, wearing clothes, drinking alcohol, engaging in trade, and killing any other animal, and declared that all animals are equal. The writing was neat, though "friend" was misspelled "freind" and one "S" was reversed. Snowball read the text aloud, and every animal nodded in agreement; the cleverer ones began learning the commandments by heart.

The simpler animals, especially the sheep, hens, and ducks, could not memorize the seven rules. Snowball therefore reduced them to a single maxim: "Four legs good, two legs bad." He argued that a bird's wing was a leg, so the slogan applied to birds as well. This maxim was painted above the commandments in larger letters, and the sheep, who took to it with enthusiasm, would bleat it for hours, often using it to interrupt debates at crucial moments.

The commandments, though presented as an unalterable law, soon proved subject to silent revision. After Napoleon's dogs had torn to pieces the animals accused of conspiring with Snowball, Clover and Muriel discovered that the Sixth Commandment now read "No animal shall kill any other animal without cause." The last two words had been added, justifying the purges. The animals had forgotten the original wording and accepted Squealer's assurance that the commandment had always included the qualification.

Following the incident in which Napoleon appeared drunk wearing Mr. Jones's bowler hat, the Fifth Commandment was found to read "No animal shall drink alcohol to excess." Muriel, reading it aloud, noticed the addition. The animals had once again misremembered, and the new version allowed the pigs to drink in moderation.

Years passed, and the farm's history was forgotten by all but a few. The windmill was completed but used only for milling corn, not generating electricity. The pigs moved fully into the farmhouse, wore human clothes, and walked on their hind legs. Squealer strolled across the yard upright, followed by a file of pigs, and finally Napoleon emerged, carrying a whip. The green flag was stripped of its hoof and horn, and the farm was renamed "The Manor Farm." The wall of the big barn now bore only a single commandment: "All animals are equal but some animals are more equal than others." The original seven had been replaced by a maxim that openly enshrined inequality. When Napoleon and Mr. Pilkington played cards, the animals outside the window saw that the pigs' faces had become indistinguishable from those of the humans. The revolution had completed its circle.