One of the original resolutions put forth by the animal leaders in their new government was that the animals would not engage in trade with neighboring farms. The idea was that the farm would be entirely independent, especially of any form of human help.
By Chapter 6, many of the animals are weak from their food shortagesand disillusioned because of the Snowball incident. So, when Napoleon announces that they will now be trading with the nearby farms, the animals cannot remain silent. Not only do they not understand why they have gone without if the farm actually has food goods to trade, but they are also puzzled by the apparent disregard of a resolution. When they voice their concerns, Squealer--Napoleon's propaganda machine--tells them that there was never any resolution against trade and makes it seem as if their own confusion caused them to think that there was. He even brings in Snowball and tells that he must have misguided them.
The whole incident represents how thoroughly under Napoleon's control the animals are. Propaganda forces them to question their memories of and original goals for the farm and their new way of life, just as Stalin controlled the minds of the Soviet people by rewriting history and incorporating powerful propaganda techniques.
It was soon became clear that certain items like "paraffin oil, nails, string, dog biscuits, and iron for the horses' shoes" could not be produced on the farm itself. These items could only be procured by trading with other human beings,
"accodingly Napoleon announced that he had decided upon a new policy. 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."
But all the animals were reminded of the earlier resolutions: "Never to have any dealings with human beings, never to engage in trade, never to make use of money" and they were uneasy and some of them even protested. But Napoleon quickly silenced all protests and announced that they would not directly deal with human beings but only through an intermediary called Mr. Whymper.
Afterwards Squealer the propaganda secretary manages to convince the animals that the earlier resolutions were purely a figment of their imagination:
"He assured them that the resolution against engaging in trade and using money had never been passed, or even suggested. It was pure imagination, probably traceable in the beginning to lies circulated by Snowball."
To those who objected he cleverly fooled them by demanding whether these resolutions existed in print. Since there was no written record of these resolutions those who objected were convinced that no such resolution ever existed.