How does physical illness relate to madness? How does one's environment relate to one's mental state in this book? What is Conrad saying about the affect of environment?

There is so much to this question that it is difficult to answer in this short space. Physical illness and environment affect most of the Europeans in The Heart of Darkness. The Congo is an alien place to these white men who come searching for her treasures. The unflinching heat, the steady sweat, the hypnotic fevers....all lead to a mental instability. The doctor, in the beginning of the story, had a rather absurd hypothesis about what happens to white men's brains/skulls in the Congo. By the end of the book we think this guy might may actually have had a point. Certainly Kurtz falls prey to this jungle madness. Perhaps this madness is the price white European men payed for robbing the Congo of her treasures and enslaving her people.