I was about twelve years old, and I was having a conversation with my mother as she was driving me somewhere. I wish I could remember what we were talking about, but in any case, the subject of sex came up.

“It’s OK; I already know all about that,” I said. As indeed I should have, since my parents had a year earlier given me a pamphlet — it was probably called “Your Changing Body,” or something like that — that explained it all. Learning about heterosexual sex was a revelation about human anatomy, similar to when plate tectonics explained why the shapes of South America and Africa fit together so well.

Granted, there were some things in the pamphlet that remained mysterious. For example, it assured me that if I had the urge to rub or stroke my penis, doing so would be perfectly normal. It was unsurprising to be told that such behavior was harmless, since rubbing or stroking anything was unlikely to cause damage, but — really? Why in the world would I ever want to rub my penis?

Another perfectly normal event it described was a “wet dream,” in which my penis would stiffen and emit liquid in the middle of the night. Except for the stiffening part, this sounded an awful lot like wetting the bed, which was definitely not normal behavior — so I wondered why the stiffening part made it OK.

In any case, I readily absorbed all of the information in the pamphlet and assumed that it would all make sense when the time came. Which is why, when the subject of sex came up, I assured my mother that I already had it covered.

“No, you don’t,” she said. “There’s so much you don’t know!”

I looked at her quizzically. The biology of it seemed pretty straightforward: When the time came when they wanted to have a child, the man and woman — most likely consulting a set of instructions to make sure they did it right — would simply insert Tab A into Slot B, and nature would take care of the rest.

“Listen,” she said. “God wanted people to have lots of children, so he made sex feel good. Really, really good. Most of what people do in life is about getting a chance to have that good feeling.”

I’m pretty sure that the conversation ended there, as we’d reached our destination. But the unexpectedly emotional tone with which she’d imparted that information made it hit me especially strongly. Most of what people do in life…?! Her comments that day gave me a new and powerful way to look at and understand human nature.

I thought of this conversation years later, when I was working as a freelance writer of educational and training materials. A client was putting together an elementary-school curriculum about drug abuse, and wanted me to write the script for an introductory video.

There was no substance-abuse education when I was in elementary school, but there was when I was in high school, and it was awful. We had to memorize each commonly abused drug and its effects: Heroin use leads to insomnia, impaired coordination, and slowed breathing. LSD brings on paranoia and hallucinations. Methamphetamine causes anxiety and hypertension. By the time we got though the whole list, I thought, “Why would any sane person want to take these drugs?” Which I guess was the point.

At the same time, I knew that plenty of people do take these drugs, and they must have a reason. Clearly there must be a pleasurable aspect of the experience. The fact that nobody was telling us about the positive side meant that we were being fed propaganda, and that nothing we were being taught could be trusted. What’s the point of going to school if you’re going to be lied to?

I wanted to be honest with kids. My video script had a bunch of neighborhood kids talking about their experiences with and feelings about illegal drugs, including what made these drugs attractive. In the end, of course, they would conclude that the downsides of drug use outweighed the upsides. Hopefully, the audience would reach the same conclusion.

My client would have none of it. Any mention of the fact that abused drugs can make a person feel better — if only temporarily — was taboo. I ended up having to write the traditional gloomy script, which I knew that students would have no reason to pay attention to.

So my question is: Why did nobody tell us about pleasure? Why couldn’t the writers of pamphlets and textbooks admit that sex (or masturbation) can be pleasurable, or that recreational use of drugs can be pleasurable? Part of understanding how the world works is understanding people’s motivations. I’m not a parent, so I don’t know whether things are different now, but I can say unreservedly that once I understood why people make the choices they do, I was much better equipped to make my own informed choices.