This essay is noted for the epiphany that Orwell experiences as he faces the elephant and, more importantly, for the "sea" of Burmese faces who have come along expecting a good show and watching Orwell as they would a magician about to pull a rabbit out of his hat. The pressure from them that Orwell feels makes him realise that, although he thinks it is completely unnecessary to kill the elephant, he will have to do it after all. The massive irony of this is not lost on him as he is the white man, the overlord, the colonial power, holding a gun, who is nevertheless forced to act in a way contrary to his judgement and experience by the will of the crowd. The truth he learns about imperialism is that "when the white man turns tyrant it is his own freedom that he destroys." Becoming tyrant transforms the white man into an "absurd puppet" or a "sort of hollow, posing dummy." By seizing power, imperialists actually paradoxically strip themselves of power.
It taught him that the expectations of the governed caused the governing people (the "imperialists") to do what the governed expected even when the "imperialist" knew without a doubt that it was the wrong thing to do.