Intriguing clues about a practice from the Middle Ages, for which one could be burned at the stake:
Metaphysical materials on sacred sexuality
L. Kevin Johnson – Spring 2011
This piece shares how one man discovered that learning to use sex as "a pure act of sharing" shifts perception in the direction of inner peace. Here's an excerpt (or read the entire piece).
... The problem we face is simple. Our fears of physical decline, of pain, of not surviving, of not feeling loved drives our ‘ego-sense of self’ within the primitive part of our brain mad and makes us grasp outwardly for relief from the discomfort we feel. Whatever we think will solve the immediate problem is what we go for and it is always determined by our conditioning, our circumstances and preferences. It doesn’t matter what form it takes because it’s always the same. We want relief from suffering.
Here's a scan from an old book by George W. Carey (esoteric Christianity author). This segment talks about the importance of conserving sexual energy in order to enhance the function of the pineal gland.
These are excerpts from an old book, in which a man who claimed to have been trained by Zarathustrians in the Iran mountains, shared his insights about lovemaking without orgasm. Hanish died in 1936.
How many people have asked you, "Seen The Secret yet?" It's a documentary about the law of attraction. The message is that our thoughts, feelings and expectations shape our experience of the material plane. The film reminds us to choose thoughts consciously, as we tend to create more of whatever we focus upon — desirable or undesirable.
If "the two becoming one" is a key piece of our spiritual awakening, what does this mean?
I drew: 4 (R): The Emperor. then: 25: The Navigator. 38 (R): Duplicity. 4 = 4 25 = 2 + 5 = 7 38 = 3 + 8 = 11 = 1 + 1 = 2 4 + 7 + 2 = 13 The answer is: 13: Immortality.
Well, I think the answer is obvious. The "two becoming one" is the way to achieve immortality.
The answer (13) is clarified by the two minor arcana (25 and 38).
25 is the Navigator
UPRIGHT MEANING: Heroic battles. Hidden enemies who must be vanquished or turned into allies. Exploration. Adventurous journey.
The Imitation says
We could enjoy much peace if we did not busy ourselves with what other people say and do for this is no concern of ours....but we are held too firmly by our passions and are too much concerned with the passing affairs of the world. We seldom completely master a single fault and have little zeal for our daily progress...the greatest and only obstacle to our advance is that we are not free from passions and lusts, nor do we strive to follow the perfect way of the Saints. But when we encounter even a little trouble, we are quickly discouraged and turn to human comfort.
Are you familiar with the Rosarium series of alchemical drawings? Jung wrote about them and at the time I was studying his commentaries I found them very interesting, so much so that I used several in my "Consummation" chapter of my book.
But when an image spontaneously came up for me a few days ago and led me back to the drawings I found myself identifying with them in an entirely new, personal, even literal rather than metaphoric or symbolic way, and speaking deeply and profoundly about the process by which "the two become one."
Not having my books with me when the image come up I searched for "rosarium alchemy" which took me to the present day motherlode of alchemical research--Glasgow--and to libraries at Glasgow U and the U of Strathclyde.
To answer this question, I used the oracle form of search, like your friend did with Thomas a` Kemp, and chose a page and paragraph from one of the Karezza booklets (Karezza: Ethics of Marriage, by Alice Bunker Stockham, MD) you have online (because my own thoughts were coming too fast to gel into anything coherent just yet, yet I knew it was all directly related to the sacredness of what we are researching), and found these lines jumping up and down for some attention:
The best development and the purest lives come from a full understanding and recognition of the purely spiritual or divine in man. The knowledge of the living, spiritual truth that man has no separate existence from God, is the most potent factor in breaking down all supposed inequalities between the sexes. This gives us a new language. There is no more talk of male or female minds, male or female qualities, for all minds are from one source. Each individual includes in his characteristics both male and female principles, both the fatherhood and motherhood of God.