זוהר ויקרא — דף מג ע”ב

When the soul emerges into the world, that same image becomes available to it and grows together with it, and man's days depend upon it, as it is said, "for our days upon earth are a shadow." And from the day a woman conceives until the day she gives birth, people do not know how great and how supernal are the works of the Holy One, blessed be He.<br />
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It is explained that all the spirits of the world comprise male and female, and when they go forth they separate, each on its own path; if the man merits it, they are joined together again as his soulmate, as it is said, "let the earth bring forth a living soul after its kind" — the man's spirit whose match, resembling him, comes forth.<br />
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Because Adam the first man and his mate sinned, the male and female separate when they come forth from above, until there is will before the Holy One, blessed be He: if the man merits it, his mate is given to him, and if not, she is separated from him. Rabbi Elazar disagrees and says that male and female are included together, and the difference lies in the side: if they are included from the right side — "and she shall bear a male" — and if from the left side, she will bear a female, for the left side dominates more than the right.<br />
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How many thousands and myriads come forth at once, and they are not called souls until they settle in the body, over thirty-three days; and during the first seven days the spirit travels through the body to find its place, as it is said, "and it shall remain seven days under its mother."<br />
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On the eighth day the spirit and body return to appear before the Mistress, and the three additional days are the days of pain of circumcision, during which the spirit has not yet set its dwelling in the body as on the other days. "The blood of purity" is said without the final heh, so as not to attribute the purity to the Mistress, but "purity" plainly.<br />
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On the commandment of circumcision on the eighth day the secret of the holy covenant is explained, as it is said, "the secret of the Lord is for those who fear Him, and His covenant, to make it known to them" — for those who fear sin alone. At the time when the holy people gather to remove the foreskin, the Holy One, blessed be He, gathers His whole entourage and reveals Himself to remove that foreskin above, for all the deeds of Israel below arouse a deed above, and a vessel is prepared for it with dust, as it is said, "and the serpent, dust shall be its bread."<br />
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Finally, on the verse "you shall not touch any holy thing," it is explained that the Community of Israel takes from the King's house sustenance for the spirits of mankind and feeds them in holiness, except for those who have not yet settled in the body; and after thirty-three days she watches over them every day until her work is complete.<br />