In 2002, I was one of several persons asked to speak at a memorial for a friend of many years. The speaker before me delivered in the manner of one genuinely delighted at learning a treasured lesson. His car had needed a new alternator, and he had priced the job at his car dealer—a very substantial sum. When he related this to our friend Ron a few years before, Ron had said, “Replace it yourself. You can use my tools, and the alternator will cost you about $65. You can do it in an afternoon.”

Pleading his ignorance—and fear—of mechanical matters, the car owner seemed resigned to paying hundreds. Ron eventually persuaded him that he could do it himself.

The way that afternoon went was this: Our friend relaxed on the lawn with his fingers interlaced behind his head, staring up at the clouds. He began, “Open the hood…”

That’s enough to discourage most people because the engine compartments of cars are full to the top with objects few of us can positively identify.

“Get out the 9/16 box wrench—the size is marked right on it—from the right side of the second drawer from the top.”

“Stand close in front of the car and look about 30 degrees to your right.” He then described the alternator in detail and the brackets and connections supporting it.

Positive identification! The rest of the afternoon went just like that: “Get out the 9/16 box wrench—the size is marked right on it—from the right side of the second drawer from the top. Now you’ll see an arc-shaped black steel strap with a slot down the middle of it.”

Of course, Ron had changed more than one alternator in his life and could see it in his mind’s eye.

In due course, step by step, the job was complete. New alternator in place, drive belt back on the pulleys and tensioned, and electrical connections restored. Upon starting the engine, the ammeter swung to the right indicating that battery charging was now vigorously taking place. Success.

The man doing the physical work found that the auto engine’s many external systems now made the beginnings of sense to him. The underhood space was no longer marked on his personal map as, “There be monsters here.” Many parts now had names, purposes, relationships.

This is how we learn best, by combining ideas and actions. The act of taking notes helps us learn the material. The many acts of mechanical work organize themselves into understanding. What was once mysterious becomes by degrees comprehensible.

Years before, Ron had set himself the task of building a 90-hp Vincent, but every time his highly modified engine reached 7,500 rpm, the crank wheels had shifted on the crankpin, which is pressed in place with many tons of force. He’d thought about that, constructing in his mind a picture of the various flexing parts. And he had decided that the flywheel shift occurred when the “elephant ears flapping” mode of the flywheels, flexing toward and away from each other, came into step with the firing frequency. At that point, the flapping motion would greatly increase, possibly enough to move those heavy press fits. In this motion, the crankpin itself was acting as the spring, and that flexure continued right into the press fits holding the pin in the wheels. That motion, combined with torque pulses from the cylinders firing, had shifted the crank.

I could see that he was right. It explained other things I’d seen. Like the man with the failed alternator, I had gained understanding from the active mind’s eye of another.