This weekend in traditional Judaism, there was a lot of talk about animal sacrifices. We read the regular daily offerings, the additional offerings for Shabbat, a Torah portion that gets into the topic, and the services for a new lunar month — it involved a lot of slaughtering. In the lunch line, two vegetarian boys in the Bat Mitzvah’s class raised strenuous objections to the prevalence of animal sacrifice in our tradition. “It’s God,” one of them said. “If He wants animals so bad, why can’t He just kill them Himself?”

There are not enough words ever spoken by humankind for me to express how much I loved this question. What surprised me is that I have an answer now: The core of that practice was not about the killing or the animals — both of which would have been easier to handle in their cultural context than they are for us. What was hard for ancient Israelites about sacrifice was offering up the choicest parts of their livelihoods in service of the Divine.

In our era — even for farmers, I would suggest — there’s something much harder for us to sacrifice now: time. That’s why the rabbis were able to successfully convert the ancient sacrifices into the lengthy prayer services we now do instead. Our spiritual practice asks us to give up a daily portion of our most precious resource in service of things beyond ourselves.

Daily meditation is a time offering. That’s one of the hard parts. But I think that’s also what accounts for the qualitative difference between sitting for 20 minutes and sitting for 30. That extra push beyond what might feel comfortable helps us get used to going beyond the bounds of our own desires. That’s great practice for living life in service to the world.