When sex is good between two people, something happens that is greater than the sum of what these two people could do alone. This is usually attributed to love, meaning, and relationship, and these aspects are surely vitally important.
Superimposition is the idea that the two energy systems of the people involve interact during sex in a very unique way. This is described as 'the earth moved' or 'fireworks' or even 'leaving the room,' in literature, but seems to be considered by 'science' to be an hallucination, probably because superimposition doesn't happen to the over-controlled and insensitive. Along with reproduction and autonomic regulation, superimposition seems to be one of the 'functions' of sex. Superimposition makes possible full discharge.