animals' illiteracy as a means of keeping them down, keeping them in a state of perpetual ignorance. For Old Major, the animals will only be able to walk tall—in a figurative sense—if they're able to read and write as well as the humans themselves.

However, Old Major's liberating message is cynically distorted by Napoleon and the other pigs once they've achieved power. They proceed to keep the other animals in a state of subjection even worse than what they experienced under Mr. Jones. And the pigs use education—or rather, the lack of it—to maintain their iron grip on power. The animals' illiteracy allows Napoleon to change the Seven Commandments of Animalism whenever it suits him. It's always easy to change the rules if no one can actually read them.

In Orwell's classic novella Animal Farm, the pigs learn to read and educate themselves after listening to old Major's moving speech regarding the need to rebel against their tyrannical human masters. The educated pigs created a system of thought called Animalism, which promotes solidarity among all animals and warns against interacting with humans. The pigs quickly begin teaching the other animals how to read and comprehend the concepts of Animalism, which motivates them to revolt against Mr. Jones. After not being fed for several days, the animals rebel and drive Mr. Jones from his farm. Initially, the Revolution is successful, which proves the power of education. Through education, the animals become aware of their difficult conditions and formulate a system of thought, which influences them to revolt against Mr. Jones. As the story progresses, the pigs refuse to educate the other animals and reserve the opportunity to learn for themselves. By retaining the privilege to exclusively educate themselves, the social gap between the pigs and the other animals increases and the pigs cement their positions of authority, knowing that the other animals are too ignorant to start another revolution.

Orwell took the message of education full circle in Animal Farm illustrating its importance, usefulness and its misuse.  Notice that one of the first thing that the pigs do is to educate themselves and sets to trying to educate the other animals of the farm.  At this point, the pigs have realized the value of education and are trying to educate the farm's inhabitants to help their society.

Unfortunately, the lack of literacy keeps the animal's ignorant and misinformed when freedom from Jones is more fully established.  The work of the farm is said to become more important and the animal's are told to adopt Napoleon's ways.

Keep in mind that originally,  Snowball was the one who set forward on the path to education while Napoleon built his army (the puppies). Snowball was the more scholarly pig (he had the plan for the windmill originally) and as he became the enemy, education fell by the wayside.