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"Peru u-Revu" and "Shevet" (1)

Harav Aharon Lichtenstein


Based on a shiur delivered in the yeshiva in 5759

Summarized by Yitzchak Barth

Translated by David Silverberg


The Source of the Halakha


     In three places in Chumash we find mention of the mitzva of "peru u-revu" (procreation).  In Parashat Bereishit (1:28), God tells Adam and Chava, "Be fruitful and multiply, fill the earth and conquer it."  Two other references to the mitzva are found in Parashat Noach: "He said to them: Be fruitful and multiply, and fill the earth" (9:1); "And you – be fruitful and multiply, abound on the earth and increase on it" (9:7). 


            In the Gemara, we find different views regarding the source of the obligation of procreation; we will discuss here several of these opinions.


            Commenting on the final verse cited, Rashi notes that the verse in Parashat Bereishit and the first verse in Parashat Noach constitute a blessing of fertility, whereas the second verse in Parashat Noach introduces the commandment to procreate.  Rashi then proceeds to cite Chazal's homiletic interpretation (Yevamot 65b), "This compares one who does not involve himself in procreation to a murderer." 


            By contrast, according to the Gemara's understanding in Masekhet Yevamot (65b), the obligation originates from a different verse.  The mishna there says:


"Men are commanded with regard to procreation, but women are not.  Rabbi Yochanan Ben Beroka says, regarding both of them it says, 'God blessed them and God said to them: Be fruitful and multiply'."


The Gemara cites the explanation of Rav Yosef that the Tanna Kama derives the obligation from a different verse, in Parashat Vayishlach (Bereishit 35:11), "I am Kel Sha-dai, be fruitful and multiply" – which was said specifically to Yaakov Avinu.  God's blessing to Adam was directed to all of Benei Yisrael; the commandment, which applies only to males, is derived from God's comments to Yaakov, to whom God speaks as an individual, as a male charged individually with this obligation, not together with his spouse.


            The Gemara in Sanhedrin (59b) implies otherwise.  There the Gemara discusses the mitzvot directed towards benei Noach and later repeated specifically to Benei Yisrael.  The Gemara notes that the mitzva of procreation was issued to benei Noach – "And you, be fruitful and multiply" – and then repeated at Sinai: "Go and tell them – return to your tents" (Devarim 5:27).  Seemingly, then, according to this Gemara, the source of the mitzva is the verse in Parashat Noach, in opposition to Rav Yosef's position in Masekhet Yevamot.


            We may, however, reconcile the two views by claiming that the verse in Parashat Vayishlach teaches only the exemption of women from this mitzva, whereas the verse in Parashat Noach serves as the actual source of the mitzva.


            The aforementioned mishna in Yevamot, as well the mishna in Yevamot 61b, speak of a mitzva called "pirya va-rivya" (based on the expression, "peru u-revu" – "be fruitful and multiply").  Elsewhere, we find discussion of a different mitzva, based on the verse in Sefer Yeshayahu (45:18), "He did not create it [the world] a waste, but formed it for habitation" ("Lo le-tohu bera'a, le-shevet yetzara").  The Gemara understands this verse as a source for the commandment of procreation, which gives rise to the question as to the relationship between these two mitzvot, "peru u-revu" and "shevet."  We must determine this relationship in two contexts – in terms of the definition of the obligation, and in terms of the limitation of its scope.


            The mishna in Masekhet Gittin (41b) writes:


"One who is half a slave and half a free man works for himself one day and for his master one day – this is the view of Bet Hillel.  Bet Shamai says: He cannot marry a maidservant, because he is half a free man; he cannot marry a free girl, because he is half a slave.  Perhaps he should abstain [from marrying altogether]?  But the world was created only for procreation, as it says, 'He did not create it [the world] a waste, but formed it for habitation'!  Rather, in the interest of maintaining the world we compel his master and make him a free man."


The mishna concludes: "Bet Hillel retracted [their position and] ruled like Bet Shamai."


            Likewise, the Gemara in Masekhet Megilla (27a) dealing with the purposes for which one may sell a Sefer Torah addresses this commandment: "A Sefer Torah may not be sold, except [to earn money for] studying Torah or marrying a woman."  The Gemara derives this halakha from "He did not create it [the world] a waste, but formed it for habitation," which it describes as a "mitzva rabba" (very important mitzva) – which surpasses in importance the purchase of objects such as a shofar or Megilla.


The Nature of the Halakha


            In their commentaries to the mishna in Gittin, the Rishonim raised the question as to why the mishna chose the verse of "shevet" as the source for the mitzva of procreation, rather than the more explicit verse of "peru u-revu."  After all, the verse of "shevet" appears in the prophets, not in the Chumash, and was not stated as a command.  Why, then, did Chazal select this verse over the more obvious "peru u-revu"?


            Tosefot in Gittin bring several answers:


1.  In order to force the master to free the servant, the situation must be such that otherwise the servant would not fulfill either of these two mitzvot – peru u-revu or shevet.  So long as the servant has the ability to observe one of these two, we cannot compel the master to free him.  Therefore, Tosefot explain, the Gemara brought the verse dealing with the mitzva of shevet, to emphasize that even this requirement cannot be observed by the servant due to his current situation.

2.  The mitzva of shevet constitutes a "mitzva rabba," and specifically on its account do we coerce the master.  The mitzva of peru u-revu, by contrast, is a mitzva like any other and would not warrant forcing the master to free his servant.  Tosefot draw proof for this approach from the aforementioned Gemara in Masekhet Megilla.  A similar source appears regarding the halakha allowing a kohen to go to the Diaspora despite the tum'at eretz ha-amim (the de facto state of tum'a Chazal declared upon lands outside Eretz Yisrael – Avoda Zara 13) if he goes to study Torah or marry.  The She'iltot explains this to mean that a kohen may go even to learn Torah or marry, and all the more so he may go for the performance of other mitzvot.  Tosefot, however, reject this view and explain that specifically these two mitzvot have the status of "mitzva rabba" whose importance exceeds that of other mitzvot.

3.  Tosefot cite a third explanation for the Gemara in Gittin from the Rivam, who claims that a gentile servant, who has the same obligations in mitzvot as women, is excluded – like women – from the mitzva of peru u-revu.  Therefore, we would not force the master to free the servant so that he can fulfill peru u-revu.  The mitzva of shevet, however, applies to everyone, including servants.  The mishna therefore chose specifically this verse, rather than the obligation of peru u-revu.  Tosefot proceed to discuss this thesis of the Rivam, that servants are included in the mitzva of shevet but excluded from the mitzva of peru u-revu.


We might suggest a fourth answer, as well.  The mitzva of peru u-revu applies to the individual; it casts a personal obligation upon each individual, like the mitzvot of sukka and matza, for example.  The obligation of shevet, by contrast, is not formulated as a command, but rather as the Almighty's will.  The assumption is that an "oved Hashem" must fulfill the will of the Creator.  (The Sefer Ha-chinukh adopts a similar approach towards the end of his discussion of peru u-revu, where he writes that neglecting this mitzva is a particularly grievous sin, as it reflects the individual's disinterest in fulfilling the will of his Creator.)  From the perspective of God's will that mankind reproduce and populate the world, it makes no difference whether one fulfills this mitzva personally or causes someone else to fulfill it.  All people bear the obligation to increase the world's population.  Accordingly, the mishna means that only due to the mitzva of shevet can we compel the master to free his servant – for he, too, shares the responsibility of populating the earth.  We would not, however, have the license to force the master to free his servant so that the latter could fulfill some personal obligation that he bears.


The Scope of the Obligation


            According to this distinction between the mitzva of peru u-revu and shevet, we can differentiate between the scope of these obligations, as well.  When it comes to the mitzva of shevet, we could perhaps take into account the current state of the world.  During the time of Adam, the world was desolate, and he bore the obligation to populate.  When, however, the earth becomes filled to capacity, it stands to reason that the mitzva of shevet would not apply.  The mitzva of peru u-revu, by contrast, would remain in force regardless of the current state of the world population.


            We could perhaps identify an additional difference between these two mitzvot, if we accept Tosefot's theory that servants and women are included in the obligation of shevet, as opposed to peru u-revu, from which they are exempt.  The Gemara in Kiddushin writes that when it comes to kiddushin (betrothal), there exists a halakhic concept of "mitzva ba yoter mi-bishlucha" – it is a greater mitzva for the woman to accept the kiddushin personally, rather than through an agent.  The Ran and Meiri understood that the "mitzva" of which the Gemara speaks refers to peru u-revu.  They then naturally asked, how does the mitzva apply to women, who are exempt from peru u-revu?  Several answers have been suggested:


A.  The Ran and Meiri answer that she assists the husband in fulfilling his obligation of peru u-revu, and regarding this role the Gemara asserts that the mitzva is performed at a higher level if she personally accepts the kiddushin.

B.  Rav Soloveitchik zt"l understood that the act of kiddushin constitutes an independent mitzva, which the woman indeed fulfills.

C.  Alternatively, one could claim that the woman plays an active role in the fulfillment of the mitzva of shevet – which includes women as well as men.


Another possible approach to the relationship between these two mitzvot is to claim that the mitzva of shevet defines the mitzva of peru u-revu, rather than comprising a separate, independent obligation.  The mishna in Yevamot (61b) writes: "One should not abstain from periya ve-rivya unless he has children.  Bet Shamai says – two males and two females; Bet Hillel says – a male and a female."  The Gemara (62a) cites two beraitot that bring this debate between Bet Hillel and Bet Shamai.  The first, consistent with our mishna, presents Bet Shamai as requiring two sons and two daughters, whereas according to the second, Bet Shamai requires a son and a daughter and Bet Hillel requires either a son or a daughter.  As a source for this final view, requiring only a son or a daughter, the Gemara brings the verse of "He did not create it [the world] a waste, but formed it for habitation."  Thus, the Gemara understood that this verse defines the mitzva of procreation, that it entails merely some contribution to the overall "habitation" of the world.  Accordingly, we should not view "shevet" as an independent obligation.


            Halakha accepts the position of Bet Hillel as recorded in the mishna, that one fulfills the mitzva by begetting a son and a daughter.  We do not follow the second version of Bet Hillel, requiring only a single child, which the Gemara attributes to the concept of "shevet."  We can understand this ruling in one of two ways.  Perhaps halakha maintains that shevet does, indeed, constitute an independent obligation and thus has no impact whatsoever on the mitzva of peru u-revu.  Alternatively, the concept of shevet actually demands begetting both a son and a daughter, and this standard determines the obligation of peru u-revu. 


            How we understand this halakhic ruling yields several practical ramifications.  As mentioned earlier, women are likely included in the mitzva of shevet despite their exemption from peru u-revu.  Does her obligation require only a single child, or must she, too, as part of her mitzva of shevet, beget both a son and a daughter?  This will obviously depend on the two approaches taken earlier.  According to the first approach, shevet requires the birth of only a single child, whereas the second possibility views shevet as involving the birth of both a son and a daughter.


            An additional difference between these approaches may emerge from a discussion in Masekhet Yevamot 62b:


"If one had children and they died, Rav Huna said, he has fulfilled periya ve-rivya.  Rabbi Yochanan said, he has not fulfilled [the obligation].  Rav Huna said he has fulfilled [the obligation], based on Rav Asi, for Rav Asi said, the son of David [= the Mashiach] will come only when all the souls in the Guf [storehouse of souls in the heavens] are taken… Rabbi Yochanan said he has not fulfilled [his obligation, because] we require 'He fashioned it for habitation,' and this has not been achieved."


The two understandings mentioned earlier leave room for discussion as to whether, according to Rabbi Yochanan, someone in this situation has fulfilled the mitzva of peru u-revu despite his having not fulfilled the obligation of shevet.  If shevet constitutes an independent obligation, then whether or not one has met the standards required by that mitzva will have no bearing on his fulfillment of peru u-revu.  If, however, we define the obligation of peru u-revu based on shevet, then failure to satisfy the requirement of shevet might preclude the fulfillment of peru u-revu. 


            (Later, the Gemara asserts that "grandchildren and like children."  Abayei and Rava argue as to whether this implies that one fulfills the mitzva by having a son who begets a daughter.  Rava maintains that one indeed fulfills his obligation in such a case, because "we require 'He fashioned it for habitation,' and this has been achieved."  Here, too, the debate might revolve around the two possibilities suggested as to the relationship between shevet and peru u-revu.)


            Further significance of this difference between periya ve-rivya and shevet arises from the Minchat Chinukh's discussion of this mitzva.  The mishna in Yevamot (22a) posits, "One who has a son from anywhere – he exempts his  father's wife from yibum."  The Gemara there explains that the mishna refers to a mamzer (illegitimate son); even if a man's only son is a mamzer, the obligation of yibum does not apply to his wife if he dies without any other children.  The Minchat Chinukh raises the question of whether someone who fathered a mamzer fulfills the mitzva of peru u-revu.  One could, of course, distinguish between a mamzer resulting from permitted relations, such as from a marriage between a convert and mamzeret, and a mamzer born from a forbidden relationship.  The Yerushalmi writes that one indeed fulfills peru u-revu by fathering a mamzer, and the Minchat Chinukh suggests two possible approaches to understanding the Yerushalmi.  First, he writes, the Yerushalmi perhaps refers specifically to mamzerim from permitted relationships.  Alternatively, it refers to all mamzerim.  Although fathering a child through an illicit relationship appears to constitute a "mitzva ha-ba'a ba-aveira" – a mitzva performed by committing a violation, the sexual act itself is only the "hechsher mitzva," the preparatory stages of the mitzva's performance.  Thus, fathering a mamzer does not classify as a "mitzva ha-ba'a ba-aveira." 


            Continuing along the lines of the Minchat Chinukh, we may distinguish between the mitzva of shevet and that of peru u-revu differently than we did earlier.  The mitzva of periya ve-rivya demands a specific action.  Shevet, by contrast, is a mitzva dependent upon the result.  According to this explanation, we can understand why sexual relations constitutes a fulfillment of the mitzva of periya ve-rivya, but not, according to the Minchat Chinukh, of the mitzva of shevet, since no children have resulted from the union as of yet.




            In this shiur we surveyed the source of the obligations of peru u-revu and shevet.  We also encountered different views concerning the relationship between these two mitzvot, as to whether they comprise two different obligations, or if we have one mitzva defined by the other.  We raised several practical ramifications of this question, involving mainly the scope of these mitzvot: the master's obligation to free his servant for this purpose, the obligation of women, and unique circumstances such as a mamzer or children who died.


            Finally, we suggested a distinction between these two mitzvot in light of the position of the Minchat Chinukh, claiming that the mitzva of peru u-revu is focused on the act required, whereas the mitzva of shevet involves the result, the production of offspring.

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