The Melakha of Boneh (Construction)

  • Rav Moshe Taragin


The mishna (Shabbat 102b) describes the melakha of boneh (construction). Typically, this activity is associated with the actual construction of buildings. However, the gemarot cite several instances in which actual constructions are not produced. In this shiur, we will explore the nature of this melakha.

Surprisingly, the gemara (95a) prohibits cheese curdling as a form of boneh, even though no land-based edifice is produced. As the Rambam asserts, any attempt to combine or fuse separate particles violates the melakha of boneh. Standard construction includes melding and merging; by extension any act of joining or amalgamating separate elements similarly violates boneh. Interestingly, several Rishonim maintain that the application of boneh to cheese making is disputed between R. Eliezer and the Chakhamim (95a), who do not envision this as boneh. Apparently, according to these Rishonim, the melakha of boneh only prohibits actual structure development, and cheese making would not qualify as such.

Several gemarot discuss aspects of construction that may not include fusion or union of separate materials. If these situations are deemed boneh, it could indicate that the melakha is defined as creating structures, and not as fusing materials.

The mishna (102b) describes an act known as metzaded, and the gemara identifies this as laying the bottom stones of a wall. Rashi traces this violation to boneh, whereas the Rambam and Rabbenu Chananel deny boneh applicability, attributing the issur to makeh be-patish. It is possible that they were debating this issue. Typically, the bottom stone is laid without cement or mortar integrating it with other stones or bricks. It is vital to the construction of the building, but it does not entail any fusion of materials. If the melakha of boneh requires fusion of materials, this may not constitute a boneh violation. Of note is the shita of the Remach (cited by the Kessef Mishna, Hilkhot Shabbat 10:18), who prohibits laying the bottom row as boneh, but only if extra stones and dirt were gathered to brace this bottom row. Perhaps he viewed boneh as fusion, such that the melakha is executed only if pebbles and dirt are employed to fasten the bottom row.

A similar question may be posed about stones on the top row, which according to the gemara were often positioned without mortar, relying on gravity to keep the stones in place. The beraita presents R. Yossi as prohibiting this isolated act as boneh, even though the top row stones are not being secured to the other rows. From the Bavli, it is unclear as to whether the Chakhamim accept this classification, but the Yerushalmi makes it patently clear that the Chakhamim disagree and base their disagreement upon the absence of any fusion of material. Evidently the Chakhamim and R. Yossi debated this very issue – whether boneh entails construction or union of materials. If mere construction is sufficient, laying the top row stones (held in place by gravity) would constitute boneh; if fusion of materials is necessary, rows of bricks positioned without mortar would be permissible.

A second scenario of construction without fusion may emerge from the case of mesatet (102b), stone manufacture and outfitting. Rav prohibits this as boneh, whereas Shmuel denies boneh applicability. Since the stone outfitting is performed without any fusing and before the stage during which fusion occurs, boneh cannot apply. (See the Rid, who claims that Shmuel denies boneh for activities performed with items that are talush.)  By defining stone shaping as boneh, Rav may be accenting construction as the core of the boneh prohibition. Any activity typically associated with construction is prohibited as boneh, even if performed without any fusion of materials.

Similar logic may drive a second machloket between Rav and Shmuel about locking in a module of a hoe or a pick. Rav bans this is boneh, whereas Shmuel does not. Leaving aside for a moment the question of boneh applicability for portable items, why shouldn’t boneh apply? Again, the Rid justifies Shmuel's denial of boneh based on the fact that no fusion of material has occurred. By simply sliding a locking mechanism into place, no previously separate materials have been bonded. In the absence of this bonding, boneh is not violated. Shmuel consistently views boneh as integration of material and denies boneh in two separate instances of construction without this fusion: carving stones and fastening components of utensils.

Perhaps the definition of boneh also impacts a different dispute between Rav and Shmuel about hollowing out a hole in a sealed container meant to house animals. The hole will allow aeration of the container, rendering it usable, and Rav therefore considers this a violation of boneh. Without providing any rationale, Shmuel argues and denies any boneh violation (choosing instead to prohibit this based on makeh be-patish). Tosafot claims that boneh would not apply because this hole allows foul air to exit the container but is not outfitted for entry. As such, it does not resemble a doorway, which typically facilitates exit and entry. Essentially, boneh only applies to activities that produce conventional architectural results. Presumably, Shmuel believes that boneh is not merely assembly-related activity, but classic construction; he denies boneh for activities that produce elements unassociated with construction. Tosafot's reading of Shmuel would then be discrepant with that of the Ri, who claims that Shmuel cast boneh as assembling different items, and therefore denied boneh in the case of fastening a lock on a shovel.

If indeed boneh entails integration of separate items, it may not apply to situations in which items were attached but not fully merged or integrated. The gemara cites a machloket between R. Eliezer and the Chakhamim about braiding hair. R. Avahu (Shabbat 94b) understood that they were debating the applicability of boneh to braiding hair, with R. Eliezer prohibiting this activity and the Chakhamim permitting. Perhaps the Chakhamim could not consider this process as boneh because the hairs are twisted together, but not physically or chemically integrated (as the materials are through the process of curdling cheese).

Finally this question – whether boneh entails construction related activities or only assembling items – may explain an interesting debate about sweeping a floor. The Ramban (Milchamot Hashem, Shabbat 94b) writes that sweeping a floor would be considered boneh, even independent of filling holes in the ground. The very act of sweeping a floor and improving the leveling of the ground (or moistening it to prevent swirling dust) constitutes a violation of boneh. Clearly, no assembly of separate elements has occurred. The only way to prohibit this activity as boneh would be to cast the boneh prohibition as construction related. Of course, the Ramban's position is still surprising, as sweeping a floor is not inherent to construction! However, the only manner of understanding the Ramban is to cast boneh as related to construction and upkeep of edifices even in the absence of integration of separate building materials.