Knight turned the machine off and on.
The machine worked.
* * *
One day a student came to Moon and said: "I understand how to make a better garbage collector. We must keep a reference count of the pointers to each cons."
Moon patiently told the student the following story:
"One day a student came to Moon and said: `I understand how to make a better garbage collector...
[Ed. note: Pure reference-count garbage collectors have problems with circular structures that point to themselves.]
* * *
In the days when Sussman was a novice, Minsky once came to him as he sat hacking at the PDP-6.
"What are you doing?", asked Minsky.