What is the energy behind sex?

The following is an excerpt from a samvaad (dialogue) session with Acharya Prashant.

Acharya Prashant: The fundamental energy of sex is man himself, mind himself. There is the source, the core, then there is the ‘I’ tendency and then there are the various forms that the ‘I’ tendency takes. Whatever be the form that the ‘I’ tendency takes, the form is utilized for the fundamental purpose of the ‘I’ tendency.