Ignition timing advance or retard

Quote from ODB Eleven forum "When your car's engine detects a fuel mixture that's too rich, it adjusts the ignition timing to occur earlier. This helps prevent the engine from getting flooded with fuel, a process known as ignition advancing.

Conversely, if the fuel mixture is too lean, the engine will slightly delay the ignition. This delay, known as ignition retarding, allows more fuel to enter the combustion chamber, balancing the air-fuel mixture."

This is an important piece of information to understand, I never really understood why delaying ignition would prevent knock. I kind off thought if knock would happen, why not get the ignition to occure sooner, so that knock would not occure. This is possibly a textbook information I slept away from, but as of now I understood it, finally...

When ignition spark is firing the amount of fuel trapped in combustion chamber is already fixed well before that so advancing or retaining ignition timing doesn't change it at all since it's requlated by valve opening and closing events, not ignition timing. What we are doing by retarding the ignition timing is two things: 1) we delay the point when the combustion chamber and piston start receiving additional heat from combustion increasing pressure and helping hot spots to arise 2) we let piston to move away from TDC increasing the volume where combustion is taking place therefore reducing temperature and pressure inside combustion chamber which are main contributing factors (apart from hot spots) for fuel to detonate...