Procreation, being fruitful and multiplying, is a central mitzva of the Torah, and since it is the most basic goal of creation, it is the first mitzva mentioned in the Torah. At the end of the process of creation, we read, “God blessed [Adam and Ḥava] and said to them, ‘Be fruitful and multiply, fill the earth and conquer it; and rule the fish of the sea, the bird of the sky, and every living thing that creeps on earth’” (Bereishit 1:28). In Parshat No’aḥ, after the flood, a similar directive is given: “God blessed Noaḥ and his sons and said to them, ‘Be fruitful and multiply and fill the earth’” (Bereishit 9:1). Finally, the admonition against murder is followed by the directive: “And you, be fruitful and multiply, abound on the earth and multiply on it” (ibid. v. 7).
By fulfilling this mitzva, a person walks in the ways of God. Just as God created the world and sustains it, people too give birth to children, take care of them, and raise them. This makes people partners with God; as the Sages say, “There are three partners in the creation of a person: God, the father, and the mother” (Nidda 31a).
This mitzva is the primary and fundamental goal of creation, as the Sages say in the Mishna (Gittin 41b), “The world was created only for procreation, as the verse states, ‘He did not create it to be empty; He formed it to be inhabited’ (Yeshayahu 45:18).” This teaches us that the most elemental divine instruction is to populate the world, as is clear when we place the just-quoted verse in context:
For thus said the Lord, the Creator of heaven, Who alone is God, Who formed the earth and made it, Who alone established it. He did not create it to be empty; He formed it to be inhabited. I am the Lord, and there is no other.
The Tanna’im state, “Whoever sustains one Jewish soul is considered by the Torah to have sustained an entire world” (Sanhedrin 37a). This is said of one who prevents a poor person from dying of starvation (Bava Batra 11a); how much greater is the virtue of parents who give birth to children, raise them, and educate them. They truly sustain an entire world.
Given the importance of this mitzva, we understand why, according to the Sages (Shabbat 31a), the third question that a person is asked when he is being judged in the next world is, “Did you engage in procreation?” (The first question is, “Were you honest in business?” The second is, “Did you set aside time to study Torah?”)
Eliezer said, “If someone refrains from procreation, it is as if he spills blood.” For the verse, “Whoever sheds the blood of man, by man shall his blood be shed” (Bereishit 9:6), is immediately followed by, “And you, be fruitful and multiply, abound on the earth and multiply on it” (ibid. v. 7) (Yevamot 63b). Having children is so essential and fundamental that one who does not fulfill this mitzva is considered to have put his children to death before they are born. R. Yaakov said, “Anyone who does not engage in procreation is likened to one who diminishes the divine image.” For the verse, “For in His image did God make man” (Bereishit 9:6), is immediately followed by, “And you, be fruitful and multiply, abound on the earth and multiply on it” (ibid. v. 7) (Yevamot 63b). Every person is unique, and therefore every person reveals an additional aspect of the divine image. Thus, one who refrains from engaging in procreation diminishes the revelation of the divine in the world.
Zohar Ḥadash (Ruth 50b) states:
When a person leaves this world and his soul prepares to take its rightful place in the next world, several angels of destruction stand on either side and several angels of peace stand on either side. If he is deserving, the angels of peace greet him warmly and welcome him. If he is not deserving, the angels of destruction greet him, saying, “Woe to the wicked man, for he shall fare ill; as his hands have dealt, so shall it be done to him” (Yeshayahu 3:11). Who is this [wicked person]? One who did not attempt to leave a child in this world, for anyone who leaves a child in this world and teaches him Torah and good deeds, the angels of destruction and hell have no control over him.
This is what is meant by the verses: “Sons are the provision of the Lord; the fruit of the womb, His reward. Like arrows in the hand of a warrior are sons born to a man in his youth. Happy is the man who fills his quiver with them; they shall not be put to shame when they contend with the enemies in the gate” (Tehilim 127:3-5). These [enemies] are the angels of destruction, who cannot control him. For a person should not say, “My Torah and good deeds protect me; I will not engage in procreation.” Rather, even if someone has studied Torah and performed good deeds, he still cannot enter God’s realm, and he has no share in the World to Come. (See ch. 8 below regarding solace for the childless.)