In order to learn anything you have to realize you don't know everything. Can know-it-alls still learn new things? How?

Can't fill a cup already full.

I used to have a saying stuck on my monitor when i had a desktop - it went like this.. 'The true sign of intelligence is being aware of what you don't know.'  Needless to say I must be hyper intelligent :P

Oh yes, they can, starting with learning they don't know it all! They have to accept the fact though, if they do want to learn anything new.

People who really know it all are already aware of the large amount of knowledge and understanding that they are unlikely to ever possess.l