For human beings, there is a constant correspondence between the stages a person goes through physically and the stages a person goes through spiritually, or developments in the body and developments in the spirit. The reason is that at the level of our souls we are born spiritual, but we are clothed with earthly material that constitutes our physical body. When our physical body is laid aside, our soul, which has its own spiritual body, enters a world in which all things are spiritual. There we associate with other spiritual beings like ourselves.
Our spiritual body has to be formed within our physical body. The spiritual body is made out of truth and goodness that flow into us from the Lord through the spiritual world. We find a home within ourselves for that goodness and truth in things that parallel them in the physical world, which are called civic and moral forms of goodness and truth. This makes clear, then, the nature of the process that forms our spiritual body.
Since there is a constant correspondence within human beings between the stages we go through physically and the stages we go through spiritually, it follows that we go through something analogous to being conceived, carried in the womb, born, and brought up.
This explains why the statements in the Word that relate to physical birth symbolize aspects of our spiritual birth that have to do with goodness and truth. In fact, every earthly reference in the literal sense of the Word embodies, contains, and symbolizes something spiritual.
The earthly references to birth in the Word inwardly refer to our spiritual birth, as anyone can see from the following passages:
We have conceived; we have gone into labor. We appeared to give birth, yet we have not accomplished salvation. (Isaiah 26:18)
You are having birth pangs, O earth, in the presence of the Lord. (Psalms 114:7)
Will the earth give birth in a single day? Will I break [waters] but not cause delivery? Will I cause delivery and then close [the womb]? (Isaiah 66:7–9)
Pains like those of a woman in labor will come upon Ephraim. He is an unwise son, because he does not remain long in the womb for children. (Hosea 13:12, 13)
from Regeneration, Pages 53, 54