Today, we pass by one of the greatest men of our century. The University of Houston's College of Engineering presents this series about the machines that make our civilization run, and the people whose ingenuity created them.

It was 1954. I was an army private at Fort Monmouth, New Jersey. I was free this particular hot summer's day, so I walked to the highway and put out my thumb. In my writing case was a thermodynamics text. I wanted to find a quiet place to write letters and to study Einstein's theory of specific heats.

The first car that stopped was going to Princeton. That seemed as good a destination as any. "Isn't that where Einstein lives?" I asked, and the man allowed that it was. I got out at the University, asked where Einstein was, and was told he worked two miles outside of town at the Institute for Advanced studies.

So I walked to the Institute and sat for an hour in its large commons room, studying thermodynamics and watching very smart people coming and going. But no Einstein. I gave up my ad hoc pilgrimage and started back to town. Where the road turned, I looked over my shoulder and saw a figure two blocks back. The sun behind him cast a brilliant halo through a mop of frizzy white hair. It was he. I stalled, watching a golf game, while he passed and strode on into town. I fell in behind him.

He walked vigorously, greeting friends and neighbors. Then he stopped and laid his briefcase on a hedge. I was terrified. Did he know I was following him? No, he was just removing his heavy blue sweater. As I passed him I saw suspenders, over a tee shirt, holding baggy trousers. He wore sandals and no socks.

That much fit the stereotype. What didn't was his substance. He was then 75 years old with less than a year left to live. But he had an earthy muscularity. He had physical grace, strength, and coordination. How many people today know that he was a good violinist? Einstein was more than just airy energy and light -- he had mass and physical presence as well.

That now-battered thermodynamics text sits on my shelf without Einstein's autograph in it. I was far too shy, unformed, and uncertain to speak to him. And the other famous names from my youth -- Roosevelt, Chiang Kai-shek, Churchill -- fade against the light, energy, and mass of this simple man, standing by a hedge, juggling stars and forces and fields in his head -- this man who made us understand that the world is more than it seems to be -- this good-humored man who insisted that, "God is subtle, but He is not malicious."

I'm John Lienhard, at the University of Houston, where we're interested in the way inventive minds work.

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For more on Einstein, see Episodes 524 and 576.

This episode has been revised as Episode 1423.