The basic ideas Old Major passes on in his first speech are that humans are the enemy because they overwork the animals and treat them badly. He says all animals should cooperate to overthrow the humans. He teaches that all animals are equal, even the wild creatures like rats and rabbits, and that they should all protect each other as friends. All humans are enemies. He warns the animals never to live in houses, sleep in beds, wear clothes, drink alcohol, smoke tobacco, touch money or engage in trade - these are all the evil habits of humans. Particularly, no animal must ever try to exert power over another animal - strong or weak, they are all brothers. As a symbol of Animalism and its ideas, he teaches them the song, Beasts of England.
Snowball, Napoleon and Squealer are the ones who develop Old Major's ideas into a complete system of thought and name it Animalism.
They determine specific principles that they can then teach to the other animals.
The pigs then reduce the principles of Animalism to seven basic commandments. These include that animals are equal, all animals are friends and all humans are enemies, and that animals should not wear clothes, sleep in a bed, drink alcohol or kill any other animal.
The Seven Commandments omit some of Old Major's original warnings, such as that animals should not touch money or engage in trade.
Although all the animals are equal, the pigs take over the leadership with the very first harvest - it is seen as natural that because they know more they should direct and supervise the others.
The Seven Commandments are then reduced to just one principle, which is written in bigger letters above the others - Four Legs Good, Two Legs Bad. Snowball...