He suggests that light is used to indicate deceit in Heart of Darkness . For example, when something glitters, it does not glitter because it is beautiful or good, but because there is something hidden under the surface, and sometimes something dangerous. The river glitters, eyes glitter. The haze is translucent, still, eerie, as though the sky was covered with white gauze. It is as though the light does not illuminate the darkness, but rather that, in a sense, the light is the darkness.
Nothing is what it seems, as is the case with a parable.
A parable is a thing that, as Jesus pointed out, you can hear if you have ears. On one level, then, Heart of Darkness is a scathing critique of colonialism. It takes place at a time when there were mere hints that colonialism was not working as it should. It was a time that appeared on the surface perhaps to be the height of Empire, a time to be bullish about colonialism in Africa. Imperialism is a central, underlying theme in this book, although it is not only about imperialism.