Musar על שבת 60:9

What she meant to say was that this seed would not live indefinitely until the era of the Messiah, but would at that time fulfill the promise of Numbers 24,17: וקרקר כל בני שת, "and he will dig up the foundation of all the children of Sheth." In Kabbalistic terms: This means that the Messiah will remove all the קליפות, the negative influences surrounding the fruit, the pure interior. At that time the world will be founded on the principles envisaged by G–d at the time of Creation. G–d will then truly derive pleasure from His creatures, death will be banished and people will live forever wearing garments woven out of light -as I have explained in the introduction to my treatise תולדות אדם. Israel will then be known as אדם, בצלם ודמות עליון, as reflecting the likeness of man's celestial counterpart. Procreation will take place at a fast pace, as described in Shabbat 30: "In the future, a woman will give birth daily. When Noach came out of the ark, however, and his descendants are described (10,1), the word תולדת is spelled defective since only the survival of mankind as a species had been assured, seeing that man had forfeited the true צלם. What man had retained was only a דמיון הצלם, a resemblance of the Divine image, something more like the דמות. The so-called צלם nowadays is more like man's shadow, צל, sometimes more visible, other times less pronounced, depending on the spiritual level of the individual.

We must understand that remark as analogous to what we have learned in Shabbat 30, that in the future a woman will give birth every day. A student asked how this could be as we cannot assume that every husband will have marital relations with every one of his wives daily? Rabbi Gamliel answered the student by referring him to the reproductive system of hens. The hens contain a whole array of ova all of which are impregnated by a rooster at the same time; the eggs are laid, however, only one per day. The sperm injected by the husband into the womb of the wife would act in a similar fashion. Not a single drop of sperm would go to waste. None of it would become evil smelling and become useless. Each drop will eventually fertilize the woman and develop into a child. Every act of marital intercourse will produce many children. Rabbi Gamliel, quoting Kohelet, tried to teach the scoffing student who had challenged the statement that in the future women would give birth daily, by demonstrating that in essence such a mechanism exists in this world. No new creative act is needed to make the prediction about man's future come true.