When I was a very young graduate student, whenever I was in New York, I’d gravitate to the Museum of Natural History. I’ve always been fascinated with the diversity of human life, including the theory of evolution.

I never missed the dinosaur exhibits. Every time I went I saw something new and interesting. Eventually, the curators came to know me, and they’d allow me into the backroom workshops where the structures were being fashioned. That was the most fascinating of all.

Everyone knows what the dinosaurs looked like, right? Everyone’s seen either the incredible displays here, or at the Smithsonian in Washington, or smaller museums. When I was in the backroom at the museum, watching them reconstruct one of the huge skeletons, I thought that was the essence of pure science.

Very rarely, of course, was the entire skeleton of a dinosaur found. For the most part, what the technicians did was to piece together a skeleton, using what they’d found in several different places. Some of the bones were real ossified bones from one site or another, and others were artificial, reconstructed bones made to replace those that were not available. These were made—in those days—of plaster of Paris.

The genius of the workers is that they were able to interpolate the parts that were missing, working with the bones they had. If they knew an animal had five vertebrae, but they had only three actual bones, they’d be able to reconstruct what the other two would look like.

Now understand, this was in the 1950s—long before I ever ran across Rabbi Feller or the Rebbe. It was long before I began piecing the elements of Judaism together in my mind. In retrospect, I believe I was potentiated, even then. My soul was cast in a Jewish mold, with only a hint of where I would ultimately find myself once I began a spiritual journey in addition to delving into the secrets of science.

Maybe the most fascinating part of it all was what today we take for granted as forensic science—first reconstructing the framework, the skeleton, then putting the musculature over it. They could tell from the way the bones grew, and how they were positioned within the body, what kind of muscular structure they supported. This takes a tremendous amount of knowledge and skill, to reconstruct how big the muscles were, how the tendons lay. They’d extrapolate from the size of one known body part, like the feet, how big the haunches were or where the spine curved. When that was done, they’d even recreate the head, based on the skull structure.

The finishing touches came when they recreated skin and produced an animal that, they said, looked like those that had actually wandered the earth. But this part wasn’t based exactly on knowledge; because of course no one has ever seen dinosaur flesh. We’ve seen mammoths—we’ve found them reasonably intact, but they weren’t of the same vintage. For the dinosaurs, it was pure speculation. Even so, when they finished, they’d take the photographs, and put them it textbooks. This, they said, is what a dinosaur looked like.

You know the pictures—the skin of a dinosaur is greenish, maybe with a muddy blue tinge. It had little stipples in it, little dimples. Way before [Steven] Spielberg, way before [Michael] Crichton and Jurassic Park, we all knew exactly what a dinosaur looked like; we’d seen the pictures in our grade-school textbooks. Obviously, we’d know a dinosaur when we saw it!

My problem was, I was a grad student. I was on a search for truth as well as life. Everything had to be consistent.

So I asked the man who was there working with it, “Why is that dinosaur green?”

And he looked at me a little strange, but said, “Because dinosaurs are green.”

Then he thought about it for a moment, and asked, “Why? What color do you think they should be?”

Believe it or not, this is a conversation that came to figure hugely in my life. It was a prime moment.

So I thought about his question. Then I said, “Well, I don’t really know. How about pink? Or they could be blue or have yellow polka dots.” Now this was way before the Flintstones, too—maybe they got the idea from me.

The technician became very offended. “That’s ridiculous,” he said. “Who ever saw a yellow dinosaur?”

To which I obviously responded: “Who ever saw a green one?”

In terms of teachable moments, that was a big one. It taught me one of life’s most valuable lessons.

I learned that science in itself contains a lot of speculation and extrapolation. A good scientist is one who uses those tools, but he knows and acknowledges the difference between what he knows and when he’s merely speculating.

That’s truth. It’s good to know.