A novice was trying to fix a broken Lisp machine by turning the power off and on.
Knight, seeing what the student was doing, spoke sternly: "You cannot fix a machine by just power-cycling it with no understanding of what is going wrong."
Knight turned the machine off and on.
The machine worked.
Important to understanding the joke is the fact that Tom Knight designed the processor for the Lisp Machine, and therefore his power-cycling is imbued with understanding.
This, in turn, reminds me of a long-shot theory about how the universe works that I sometimes ponder.
I can't think of how many times someone has come to me with a computer problem, or I've gone to a vendor/support chat with a problem that hasn't worked dozens or hundreds of times. Then suddenly, with the guru there, whether it is me or someone else, suddenly the problem evaporates.
I've found myself wondering if this wasn't some illusion, but an actual artifact of the nature of the universe. Think about it: if noob's problems everywhere were actually the universe not letting their shit work, there would be no one to ever notice it; because when the expert comes in and fixes it, it is magic to the noob anyway, and the expert is 100% used to mundanes not having their stuff work for any given reason.
Reading over jwz's travails with computers of various kinds, he seems to have an amazing amount of it for someone who used to be a professional programmer.
At the risk of causing a bunch of you to spend the rest of the day watching the whole 3 seasons of The IT Crowd....The canonical answer to 'Have you tried turning if off and on again':
http://www.youtube.com/watch?v=nn2FB1P_Mn8
If your Iphone starts blinking or vibrating randomly or does something weird repeatedly, do you take 10 minutes to understand what is happening or do you just turn it off/on?
A novice was trying to fix a broken Lisp machine by turning the power off and on.
Knight, seeing what the student was doing, spoke sternly: "You cannot fix a machine by just power-cycling it with no understanding of what is going wrong."
Knight turned the machine off and on. The machine worked.