What have you witnessed someone do that made you realize he or she is really, really smart?

My wife's grandfather. He's a retired electrical engineer with a dozen patents to his name and a long

list of recognitions I can't be bothered to remember or name. I always knew he was brilliant,

but never realized just how until one day last year we were visiting and he got a phone call. Keep in mind he's

been retired for 20 years and is 86 years old. The phone call was from an electrical engineering

firm from halfway across the globe asking if they could fly him out to a site and have him consult

on the energy capture of a hydroelectric dam they were building. They'd run into a problem that none of them

all the electrical engineers could solve. They had consulted three of the top university departments

in the U.S. on the issue, and the last one had referred them to him. 20 minutes on the phone,

and he agreed to think about it. Two days later, he'd solved their issue and written the solution

on a single 8 by 11 sheet of paper which he scanned and

emailed to the company. He said he took so long to write it up because he didn't want to have

to fly all the way out there at his age. His explanation was so clear I was able to understand and

follow it with no relevant higher education. I spent a year trying to track down an intermittent

issue with my car. An older gentleman on the

forum had suggested a likely cause, but I disregarded it as the parts had already been replaced.

Sure enough, he was right, and I managed to follow from that to find the other half of the problem.

Saved me so much trouble. I had a mechanic look at it. I'd spent hours tearing my hair out trying

to fix it. Nothing worked prior to that.

Respect your elders, folks. He should write a book slash, at the bare minimum, document what

he knows so that it can be converted to a book, or just published publicly. He's clearly

an expert in his field, and his knowledge is invaluable. Everything he can write down can

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