In the end, Boxer's death speaks largely to a couple of elements on the farm. The first would be that Napoleon's absolute control over the farm is represented. He is able to extract what he can out of Boxer and when he is no longer useful, Napoleon negotiates his "exit." The second thing shown is that the animals are really powerless to help Boxer. Napoleon had constructed Boxer's exit in such a manner that the animals only recognize too late what was happening. Muriel tries to sound out the words on the carrying truck. Clover yells out to Boxer that he is being taken to the Knacker's. Even Benjamin, who usually fails to care about anything, is motivated to try to take action to help out his friend. The lesson that is shown through Boxer's death is twofold. The first is that Boxer ends up suffering at the hands of the political establishment that he loves so very much. His implicit trust of Napoleon and the animals is what ends up killing him. The second half of this is that the animals are made aware of their powerless condition, demonstrating that the pigs are in charge and little can change that. This lesson ends up substantiating Orwell's belief that power can be manipulated to consolidate support and strengthen the control of those in the position of power.