People do not know what man is. They have to do with a very complex machine, far more complex than a railway engine, a motorcar, or an airplane-but they know nothing, or almost nothing, about the construction, working, or possibilities of this machine; they do not even understand its simplest functions, because they do not know the purpose of these functions. They vaguely imagine that a man should learn to control his machine, just as he has to learn to control a railway engine, a motorcar, or an airplane, and that incompetent handling of the human machine is just as dangerous as incompetent handling of any other complex machine. Everybody understands this in relation to an airplane, a motorcar, or a railway engine. But it is very rarely that anyone takes this into account in relation to a man in general or to himself in particular. It is considered right and legitimate to think that nature has given men the necessary knowledge of their machine. And yet men understand that an instinctive knowledge of the machine is by no means enough. Why do they study medicine and make use of its services? Because, of course, they realize they do not know their machine. But they do not suspect that it can be known much better than science knows it; they do not suspect that then it would be possible to get quite different work out of it.
– P.D. Ouspensky, In Search of the Miraculous; The teachings of G.I. Gurdjieff