In my alternate life, I’m a teacher. Worse, a preacher. Someone with the naiveté to believe that in this day and age, one person can actually instruct another’s life.

As soon as people hear what I do, I get lots of advice. I must have heard from hundreds of generous people who, though they adhere to a “live and let live” ethic, are nevertheless willing to advise me on my interventionist endeavors.

Since there’s no way of knowing how long such generosity will continue, I’ve decided to summarize the advice I’ve received over the years, for future practitioners of my craft. Luckily, it basically boils down to three important no-nos. If you avoid these three mistakes, you’re well on the way to becoming a successful educator.

Piece of Advice #1: Don’t try to challenge consensus. There are certain arguments that you’re just not going to win. Once an opinion or practice becomes entrenched in a society, you’re wasting your time. Save your energy and talents for telling people what they do want to hear. You’ll accomplish much more that way. (Unfortunately, this piece of advice came after the speech in which I claimed that a Jewish marriage, by definition, is a union between a man and a woman, both of whom are Jewish. Luckily, it came before the panel discussion in which I was going to suggest that ceding territory to a people who hate you enough to kill their own children to kill some of yours won’t bring peace but more bloodshed.)

Piece of Advice #2: Don’t bother with the lost cases. Those who have gone beyond the pale are too far gone to bring back. If they’re doing something that’s so wrong, there’s obviously something very wrong with them. Save your energy and talents for normal people. You’ll accomplish much more that way. (That piece of advice came just in the nick of time. I was actually scheduled to give a course in “The Non-Violent Resolution of Conflict” at Riker’s Island.)

Piece of Advice #3: Stay away from the G‑d stuff. Unless there’s some sort of angle. If it’s in the context of philosophy or theoretical physics, that’s okay. Spirituality is fine, too. But G‑d as in “we do that because G‑d said so” is way out there in uh-uh land. It just won’t wash.

There are three places where the Torah refers to the task of the educator: 1) in the 17th chapter of Leviticus, where it speaks of the prohibition against eating blood; 2) in the 11th chapter there, where it forbids the consumption of insects; 3) in the opening verses of the Parshah of Emor (Leviticus 21), where it discusses the laws of ritual impurity pertaining to priests. In each of these three places, the Torah employs language that is interpreted by the Talmud to mean that “the elders are enjoined to charge the youngsters” regarding these laws.

Jews have always been big on education. Indeed, the idea that elders do indeed have something of value with which to charge the youngsters—and that the youngsters will actually listen to the elders—is largely responsible for fact that we’re still around after four thousand years. But why does the Torah choose these three particular instances to convey this idea?

The Lubavitcher Rebbe, Rabbi Menachem Mendel Schneerson, of righteous memory, explains that these three laws represent three areas in which it is commonly believed that education is futile—that there’s no point in trying to influence another person.

The Talmud points out that in biblical times, the consumption of blood was commonplace. Society literally “wallowed in blood” as a dietary staple. To forbid the consumption of blood in 1300 BCE Canaan was akin to, say, forbidding hamburgers in 21st-century America. Insects, on the other hand, are things “that are repulsive to human beings.” Forbidding them seems equally futile: if a person has descended to such dietary degradation, would he desist simply because his “elders” instruct him to?

Finally, the laws of ritual impurity violate the third educational no-no. In general, the mitzvot of the Torah can be divided into three categories: a) Laws, such as “do not kill” and “do not steal,” which any logical mind would have conceived on its own; b) Testimonials, such as resting on Shabbat and eating matzah on Passover, which serve a ritualistic-commemorative function: we may not have thought these up on our own, but after they’ve been given to us, they make sense; c) completely supra-rational decrees. A prominent example of the “decrees” are the laws of ritual impurity, which defy all logical explanation; we observe them simply and exclusively because G‑d told us to.

Education, the Torah is telling us, works not because and when the educator is convincing and the educated is willing to be convinced. It works because and when it carries the power of truth. And a truth is true regardless of where society stands vis-à-vis this truth, and regardless of where an individual stands vis-à-vis this truth.

And a truth is true also when our only handle on its truth is the fact that G‑d said so.