Sheep are the animals who have been domesticated the longest in history. Because of this long domestication which has involved their being herded by man and dogs, sheep have lost any independent thought that they may have long ago possessed. Because they are now an animal that follows one another without thinking, the term "sheep" has been applied to unthinking people who are easily led by others.
Therefore, in his allegory, Animal Farm, George Orwell characterizes the sheep as rather dim-witted animals who can easily be influenced. When the seven commandments are written, some of the animals cannot understand all of them, so these rules are condensed for them to the general rule, "Four legs good, two legs bad!" When Frederick cheats the animals, But, after Napoleon runs off Snowball and becomes dictator, the animals notice that he begins trade with neighboring farms, and he changes other policies. The four young pigs raise their voices to object to the abolishment of meetings, but Napoleon's dogs silence them; because of their conditioning, the sheep bleat, "Four legs good, two legs bad," but their cry is "smoothed over."
Then, in Chapter VII, rumors are spread that Snowball and certain ones of the animals are in league with him. An interrogation is made and three hens are slaughtered.
Then a sheep confessed to having urinated in the drinking pool--urged to do this, so she said, by Snowball--and two other sheep confessed to having murdered an old ram, an especially devoted follower of napoleon, by chasing him round and round a bonfire when he was suffering from a cough. They were all slain on the spot.
Clearly, the sheep are unthinking animals, swayed easily--even to their own deaths. They are the "yes-men" of society. Further, in Chapter X, as the animals' lives become more and more arduous, Napoleon emerges one day walking on two legs. At first the animals are shocked. Then, there is a moment in which "they might have uttered some word of protest." But, Orwell writes, the sheep, as by a signal, all bleat at the same time loudly, saying,
Four legs good, two legs better! Four legs good, two legs better! Four legs good, two legs better!
The sheep are, indeed, mere followers. Never do the sheep exercise any independent thought or display any courageous action or exhibit any leadership.