The difference between mad people and sane people... is that sane people have variety when they talk-story. Mad people have only one story that they talk over and over.
Perhaps as good a classification as any of the main types is that of the three lusts distinguished by traditional Christianity - the lust of knowledge, the lust of sensation, and the lust of power.
It was also Hegel who established the view that the different philosophic systems that we find in history are to be comprehended in terms of development and that they are generally one-sided because they owe their origins to a reaction against what has gone before.

