Animal Farm by George Orwell

They explained that by their studies of the past three months the pigs had succeeded in reducing the principles of Animalism to seven commandments. These seven commandments would now be inscribed on the wall; they would form an unalterable law by which all the animals on Animal Farm must live for ever after. With some difficulty (for it is not easy for a pig to balance himself on a ladder) Snowball climbed up and set to work, with Squealer a few rungs below him holding the paint-pot. The commandments were written on the tarred wall in great white letters that could be read thirty yards away. They ran thus:
The Seven Commandments
Whatever goes upon two legs is an enemy.
Whatever goes upon four legs, or has wings, is a friend. No animal shall wear clothes.
No animal shall sleep in a bed.
No animal shall drink alcohol.
No animal shall kill any other animal.
All animals are equal.”
Until one fine day, it was discovered that:
“All Animals Are Equal But Some Animals Are More Equal Than Others.”