After surveying the ground, Snowball declared that this was just the place for a windmill, which could be made to operate a dynamo and supply the farm with electrical power [to] light the stalls and warm them in winter . . . [The animals] listened in astonishment while Snowball conjured up pictures of fantastic machines which would do their work for them while they grazed at their ease in the fields or improved their minds with reading and conversation.

Snowball champions construction of a windmill in order to provide electricity that would benefit the lives of all the animals on the farm. Not only would they have electric lights and heat, but the machinery would help them complete their labor. For Snowball, the windmill symbolizes progress; the animals took over the farm to better their own conditions, and the purpose of their work—including building the windmill—is to provide a better lifestyle for all inhabitants of the farm.

From now onwards Animal Farm would engage in trade with the neighbouring farms: not, of course, for any commercial purpose, but simply in order to obtain certain materials which were urgently necessary. The needs of the windmill must override everything else, he said. He was therefore making arrangements to sell a stack of hay and part of the current year's wheat crop, and later on, if more money were needed, it would have to be made up by the sale of eggs[.]

In this quote, Napoleon declares that the animals will begin selling farm products in order to earn money to buy materials to build the windmill. With this declaration, Napoleon announces that they will renege on one of the main principles guiding the Rebellion: not engaging in trade. No longer serving as a symbol of progress, the windmill transforms into a symbol of the corruption of the ideals that led to the establishment of Animal Farm.

Out of spite, the human beings pretended not to believe that it was Snowball who had destroyed the windmill: they said that it had fallen down because the walls were too thin. The animals knew that this was not the case. Still, it had been decided to build the walls three feet thick this time instead of eighteen inches as before, which meant collecting much larger quantities of stone.

Napoleon blames the collapse of the windmill on Snowball’s sabotage, not inadequate construction, and the animals agree. The windmill now symbolizes the gaslighting, or psychological manipulation, that the pigs have inflicted on the rest of the animals. The history of Napoleon’s rule has been denying the truth and telling the animals not to believe the evidence they’ve seen with their own eyes. Now, even though the windmill has collapsed because Napoleon knew nothing about construction and simply stole Snowball’s idea, the animals still believe that the windmill provides proof of Snowball’s treachery.

When they got up again, a huge cloud of black smoke was hanging where the windmill had been. Slowly the breeze drifted it away. The windmill had ceased to exist!

After coming under attack by the humans, the animals watch without understanding as Frederick deliberately blows up the windmill. Once again, the windmill has collapsed, this time not through their own incompetence but through warfare. The windmill symbolizes both the animals’ vulnerability and their defeat. Throughout the history of their interactions with humans, the animals have always emerged on top, but now they have been outsmarted.

The windmill had been successfully completed at last, and the farm possessed a threshing machine and a hay elevator of its own, and various new buildings had been added to it. . . . The windmill, however, had not after all been used for generating electrical power. It was used for milling corn, and brought in a handsome money profit. The animals were hard at work building yet another windmill; when that one was finished, so it was said, the dynamos would be installed.

Even when the farm has a functional windmill, the animals still see no personal benefit because the windmill and the other technological advancements are used only for production and profit, not the workers’ comfort. Despite experiencing no improvement in their daily lives, the animals are building another windmill. By this point, the windmill stands as a physical representation of Napoleon’s lies. The animals have become willing participants in Napoleon’s deception, accepting his promises of improved circumstances though they see only worsening conditions since the takeover of the farm.