As time goies on, the subconscious alters not only his conscious mind, but hois body, and even the external world. The scientist turns himself into a earlier form of man, wanders around the zoo, eats a few antelopes, that kind of stuff. In the scientific theory according to the film, the collective subconscious is the source of religious belief, superstition, sexual desire, carnivorous behavior, and heaven knows what not. There may well be a lot of scientific truth to the theories, although the plot added details which could only be called highly speculative. Those who study the human mind have been able to use hypnosis to achieve some extraordinary things - to cure disease, to end madness, to regress people to their own childhoods, and even to take people into a state where they seem to be able to do the impossible.
People are able to speak fluently in languages they have never studied, etc.
We've conquered outer space, but we are a long way from understanding our own inner space. Blair Brown is seen topless in a sex scene with Hurt, then topless again in a fantasy where his mind morphs her back and forth into a lizard, then nude from the rear as the film ends. He shows dreams, fantasies, and hallucinations in every movie. In this one it actually made some sense. The premise of the film was really excellent.