It’s amazing how one single verse in the Torah can make such an impact.

In a Torah portion filled with perspectives on and rules for kohanim, including marriage and family deaths, the cycle of the holidays, rules about sacrifices, and even a narrative about the “mekalel” — a “half-Jew” who cursed God’s name — which verse could I be referring to?

The answer will surprise you.

But first, a story. I met a woman recently who told me that what she does is rescue dogs who are going to be euthanized. Every week. It seems that once dogs are in a shelter for a certain amount of time and not adopted, the shelters kill them to make room for others. What this woman does, as part of a company called “Grateful Doggies,” is transport dogs from as far away as Greenville, N.C., to a shelter in New Jersey. From there, they can be adopted by homes that will care for them. She and her friends drive large trucks with 70 dogs in crates on a three-day binge (no sleeping or rest breaks) each week, picking up and dropping off dogs at shelters on the tightest schedule possible. (They only allow 18 minutes at each shelter. Think matzah.) If they get behind schedule, the dogs will be killed before they can reach them. She said the dogs are so cute, they give them Grateful Dead song names, like Sugar Magnolia and Casey Jones. They transport the dogs to freedom in the North, kind of like the Underground Railroad. It is grueling and dangerous work.

She mentioned that there are so many dogs to be cared for because their owners didn’t act responsibly by spaying or neutering their pets. My ears pricked up at this mention, because I know some of the history of debates about spaying and neutering is based on Lev 22:24. “Any animal that has its testicles bruised or crushed or torn or cut you shall not offer to the Lord; nor shall you do that within your land.” This verse is the single source upon which all halachic (legal) decisions about say-roos (castration) of animals and humans, for sacrificial purposes or for any other reason, physically rendered or even chemically blocked (think birth control medicine, discussed in the Talmud as “kos shel ikkarin” — a cup of roots from a certain plant) are based. The history of this body of halacha extends from the earliest rabbinic period all the way through today, and affects not merely personal issues with pets or permitted methods of contraception for observant Jews, but public policy on the question of, say, the use of oxen (castrated and thus domesticated bulls, used widely as the trucks of ancient times — think Chad Gadya) or the infamous feral cats of Jerusalem in our own time.

Along the way, rabbis have answered all sorts of contiguous questions. Are Jews allowed to even own dogs and cats (the answer is not, as you might think, self-evident), and if so, what responsibilities devolve on such owners? Can a rooster be “neutered” by cutting off its showy coxcomb, rendering it unable to attract a mate?

Although the Torah in our pasuk seems to present a straightforward and delimited case regarding sacrificial animals, the truth of the matter is that in any legal system, the basis of adjudication responds both to logic and to people’s legal needs, sometimes in farflung places, centuries, and circumstances. Despite the way we may think of such issues — the Torah speaks and we obey (or we don’t) — the actual practice of halacha is that we hold the Torah dear and sacred, and we move forward into a sometimes unrecognizably foreign and demanding world of experiences, holding fast to that which we have found to be holy and useful in addressing the new.

Lag B’Omer, coming this week, places a human and rabbinic historical situation over the biblical substrate of the requirement to bring the omer, a sheaf of grain, as a communal “sacrifice” in this time of year.

Rather than seeing such connections as tenuous or flimsy, however, perhaps we can learn from such development that the fire of revelation continues to burn brightly for those who care to see. It is in this manner that “one (set of) ruling(s) shall be for you and for the stranger who lives among you, for I am the Lord your God” (Leviticus 24:22). By building on such precedents and taking the demand that we “follow the Torah” seriously, we Jews become a long but flexible cord stitching together the realms of heaven and earth.