So, to begin:
The word sex is derived from the Latin "secare," meaning "to cut off."
The roots of this word indicate the androgynous nature of our ancestors as described in all religions, and even by Plato, and is hidden in symbols in every mystical tradition. Sexual cooperation between man and woman only began when the two halves of the androgynous being were "cut off" from one another. Vestiges of this ancient past are readily visible in the physical shadows of the man's inert nipples and the woman's clitoris, which is a shrunken penis. Thus, "sex" refers to the joining of what was separated long ago: male and female. Yet, there are levels and levels of sexual activity, ranging from the simplest forms of sexual union among minerals, plants, and animals, up to the divine sexual acts that create planets, solar systems, and universes. Sex is far more than what modern society thinks it is. In reality, sex is sacred, and a source of incredible, untapped power.
“The physical union of a man and a woman, in essence, is a supernatural act, a reminiscence of paradise, the most beautiful of all the hymns of praise dedicated to the Creator by the creature; it is the alpha and the omega of all creation.” - Samael Aun Weor
"Sexual energy is divided into three distinct types. First: the energy having to do with the reproduction of the species. Second: the energy having to do with the spheres of thought, feeling and will. Third: the energy that is found related with the world of pure Spirit." - Samael Aun Weor
"...the controlling of the sex nature builds up a reservoir of strength, and it is this strength that opens the door to the Innermost." - M, The Dayspring of Youth
"Sexual pleasure is a legitimate right of the human being." - Samael Aun Weor, The Three Mountains