Highly speculative solution by lavalyn:
KarlKnechtel: I'm convinced this is it. I saw as playing at what looked like a key point of the space surrounded by Black, and also making good shape - but the shape I saw was the nameless one made by and the stones. :)
unkx80: Sometimes good feeling is important in life and death situations. Often good feeling can help one in making the correct choices, such as in this diagram. But this feeling needs to be cultivated.
Of course, if there were a stone (black or white) at a, this defence wouldn't work because of shortage of liberties.
byorgey: If Black plays , then White ataris with , leading to the same configuration seen in the diagrams above.
Just trying to create eye space doesn't work - Black makes an eye false.
Moosky: I think Black answering directly at (instead of ) is even better. If at , then at the circle.
lavalyn While doing some revision and a bad edit: