The functions of the human frame are, broadly speaking, known. They are a country, anyhow, that has been charted and mapped out. But outside that lie huge tracts of undiscovered country, which certainly exist, and the real pioneers of knowledge are those who, at the cost of being derided as credulous and superstitious, want to push on into those misty and probably perilous places. I felt that I could be of more use by setting out without compass or knapsack into the mists than by sitting in a cage like a canary and chirping about what was known. Besides, teaching is very very bad for a man who knows himself only to be a learner: you only need to be a self-conceited ass to teach.