Today, we ask if successful inventors are just lucky. 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.

This afternoon an interviewer asked me if invention is a matter of luck. I hadn't thought much about luck, but the question woke me up. We certainly find lots of lucky inventions.

Those little yellow Post-it notes were invented after a chemist accidentally created a glue that wouldn't dry. That was blind luck, no doubt. But it did no good until someone recognized how glue that doesn't dry can serve us.

The history of chemical process technology teems with examples like that -- everything from rayon to dynamite to vulcanized rubber. In each case, an accident happened -- maybe one that'd befallen a hundred other people. But only one person was prepared to recognize possibility when it was out of context.

Louis Pasteur discovered that molecules with the same chemical structure can be either left or right-handed. Two otherwise identical molecules can have radically different properties. That may've just been the result of a lucky observation. But Pasteur pointed out that "chance favors only the prepared mind."

So: to receive luck we have to prepare our minds. A good invention is like a good joke. The joke teller leads you out on one plane of reality. Then, suddenly, in the turn of a phrase, you find yourself standing in another reality entirely.

The old Burma-Shave ads did that. Six red signs along the road: "IF HARMONY, IS WHAT, YOU CRAVE, THEN GET, A TUBA, Burma- Shave." In 8 seconds of drive time we're carried from harmony in human relations, to musical harmony, to a tube of shaving cream creating harmony on your face. It may've been simple-minded humor, but recognizing those lurches of meaning delighted us anyway.

In that sense, James Watt caught on to a joke when he improved the steam engine. For 70 years we'd squirted cold water into cylinders filled with hot steam. Steam condensed and sucked the piston down. But that water cooled the cylinder. You wasted half your steam warming it back up to repeat the cycle.

It took Watt years to see. Then he caught on. He realized that if we led steam out into a separate condenser, the cylinder would stay hot. The condenser would always be cold. All at once, Watt doubled steam engine efficiencies.

Now, was Watt lucky? Of course he was. But that same lucky perception had lain in wait for hundreds of engine-builders before him. Luck is before us, all the time. We just have to recognize it when it walks by.

"Sure," I told my interviewer, "invention's a matter of luck." But oh, how few of us are able to let go of our limitations and open our eyes to the ever-present gift of good fortune.

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

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