Within this week’s parshah lies a section of laws aimed apparently at preserving the integrity of biological species. Its first half contains prohibitions upon crossdressing (Deut. 22:5), seizing a mother bird along with her chick (ibid. 6-7), crossbreeding (ibid. 9), plowing with an ox and donkey together (ibid. 10), and wearing mixtures of wool and linen (ibid. 11). From there we proceed to a series of matters that concern various forms of forbidden union between men and women (ibid. 13-23:19).
In the middle of this section, however, we discover a law that does not seem thematically related to the subject at hand: “גדלים תעשה לך על ארבע כנפות כסותך אשר תכסה בה”—“You shall make yourself twisted threads, on the four corners of your garment with which you cover yourself” (Deut. 22:12). Why is this mitzvah—the mitzvah of tzitzis, i.e., of affixing knotted strings to four-cornered garments—included here?
Rashi, citing Chazal, tells us that the mitzvah of tzitzis is juxtaposed with the ban upon shaatnez, i.e., of wearing mixtures of wool and linen, in order to teach us that this ban may be lifted for the purposes of producing tzitzis. This approach explains how the mitzvah of tzitzis fits within its immediate literary context. Yet if we wish to account the role of tzitzis within the overall framework of our passage, then we must determine whether this mitzvah is somehow connected with our passage’s main topic—namely, illicit biological mixtures.
As a matter of fact, the mitzvah of tzitzis, from this vantage point, could hardly be better positioned. As mentioned, the portion of laws introduced by the mitzvah of tzitzis address sexual relations which the Torah deems improper. It so happens that the Torah applies a most fascinating euphemism to one who engages in such relations: he is said to have been “גלה כנף,” i.e., to have “uncovered the corner” of a garment not belonging to him. Typical of this idiom is a verse which appears only a few verses removed from our verse about tzitzis: “לא יקח איש את אשת אביו ולא יגלה כנף אביו”—“A man may not take his father’s wife, nor shall he uncover the corner of his father’s cloak” (Deut. 23:1). Surely it is to prevent precisely such behavior that the Torah provides us with the mitzvah of tzitzis: a mitzvah which requires us not only to keep ourselves robed with “כסותך אשר תכסה בה” (literally, “your covering with which you cover yourself”), but which charges us as well to add “גדילים” (semantically, “growths” or “extensions?”) to the garment’s “כנפות” (its “corners”). Indeed: What better bulwark against the sin of “uncovering the garment’s corner” than a ritual which extends the corners of our own garment, so that we must think just a little longer before overturning them?
It can be no coincidence, in this vein, that elsewhere the Torah provides the following well-known rationale for the mitzvah of tzitzis: “They shall make for themselves fringes on the corners of their garments… a thread of sky blue on the fringe of each corner… in order that you shall not wander after your hearts and after your eyes after which you lust [זנים], so that you shall remember and perform all My commandments and you shall be holy [קדשים] to your God” (Num. 15:38-39). Though, in large part, tzitzis serve to remind us of our obligation in all mitzvos (a wonderful “fringe benefit,” to be sure!), the terms associated with tzitzis both here and in our parshah suggest that it is the value of sexual propriety, in particular, which they primarily represent. And this view is clearly reflected by Chazal as well; hence, for instance, the Talmudic tale of a certain sage who nearly succumbed to promiscuity reaches its climax when—of all possible outcomes—he is physically restrained by his tzitzis (Men. 44a).
Of more direct daily relevance: This interpretation of tzitzis also frames most meaningfully the ashkenazi custom per which men begin to don the tallis (the prayer shawl adorned with tzitzis) on the occasion of their marriage. Though the Jewish wedding involves no ceremony of “tying the knot,” the “tied knots” of tzitzis stand as tangible tokens for the newlywed husband of the sacred commitment to which he has bound himself, and warn him against trying to “cut any corners” in its fulfillment. Should he, instead, uphold it faithfully, as is expected, he invites great blessing into his life:
How precious is Your kindness, O God; humanity seeks shelter in the shadow of Your wings (alternatively: of Your “corners”—כנפיך)…. For with You is the source of life; in Your light we will see light. May you extend Your kindness to those who know You, and Your righteousness to the upright of heart (Ps. 36:8-11; from the prayer recited before donning the tallis).