“In sex life, the combination of matter from the parents, which involves emulsification and secretion, creates the situation whereby a soul is received within matter, and the combination of matter gradually develops into a complete body. The same principle exists in the universal creation: the ingredients were present, but only when the Lord entered into the material elements was matter actually agitated. That is the cause of creation.” (Shrila Prabhupada, Shrimad Bhagavatam, 3.26.51 Purport)