Madness in "Heart of Darkness"

The idea of madness pops up as a reoccuring theme throughout "Heart of Darkness."  "He gave me a searching glance and made another note. 'Ever any madness in your family?' he asked in a very matter-of-fact tone.  I felt very annoyed.  'Is that question in the interests of science too?' 'It would be,' he said, without taking not of my irritation, "interesting for science to watch the mental changes of individuals, on the spot..." (Conrad, 26).  This encounter between Marlow and the doctor sheds light onto the idea of madness caused by going into the 'heart of darkness.'  Throughout the early stages of the novel, it is mentioned on multiple occasions by many people that Kurtz himself has gone mad.  However, as we, the readers, and Marlow begin to learn more about and encounter Kurtz, we begin to sympathize with him more, bringing up the question: What truly is madness?  It is apparent that Kurtz's so-called madness has come about as a result of his near isolation in the Congo, as he has basically become his own authority.  With Kurtz so far removed from European civilization, the only man he need answer to is himself.  This results in Kurtz's near tyrannical ruling of the tribal people, and his greed filled yearning to collect ivory by any means possible.  Kurtz's madness is caused by his absolute power in his new residence, something that sheds light onto the human condition as a whole.  Absolute power without authority is often too much for one man to bear, especially when removed from one's natural social context.