This fact is one of the secrets which were known to the ancients, but have now been lost. The ancients knew that every single thing which takes place in the body has a spiritual source. Actions, for instance, arise from the will, which is in essence spiritual; speech arises from thought, which is also spiritual; natural sight arises from spiritual sight, which is understanding. Natural hearing arises from spiritual hearing, which is the application of the intellect and at the same time the adjustment of the will; and natural smelling from spiritual smelling, which is perception; and so forth. The ancients saw that the male production of semen was from a spiritual source, and they concluded from many proofs afforded by both reason and experience that its source was the truths of which the intellect is composed. They also said that what males received from the spiritual marriage, that between good and truth, which influences every detail of the universe, is nothing but truth and what refers to truth; and this as it progresses into the body is formed into semen. This is why seed understood spiritually means truth.

[2] As regards its formation, they said that the male soul is truth because it is intellectual; for what is intellectual is nothing else, so when the soul comes down, so does truth. This takes place by the soul, which is the inmost part of a person and of every living thing and is in its essence spiritual, having an inborn striving to propagate itself, so as it comes down the soul follows and wishes to recreate itself. When this happens, a whole soul forms and clothes itself, becoming a sperm. This can happen thousands and thousands of times, because the soul is a spiritual substance, having no extension, but fullness. No part is taken away from it, but the whole is reproduced without loss. This is why it is fully present in the tiniest receptacles, the sperm, just as it is in its major receptacle, the body.

[3] Since then the truth of the soul is the source of the seed, it follows that men's potency depends upon their love of propagating the truths of their wisdom. It is also dependent upon their love of performing services; and this is because services are examples of goodness, which truths bring forth. Even in the world some people are aware that potency is found with the active, and not the idle. I asked how the female is propagated from a male soul. The reply I received was that this is from intellectual good, because this is in its essence truth. For the intellect is able to think that something is good, and so that it is true that it is good. It is different for the will, which does not think about good and truth, but loves and does them. Therefore sons in the Word mean truths, and daughters instances of goodness (see 120 above); and seed in the Word means truth (see THE APOCALYPSE REVEALED 565).