We lived in the same city for a while (Bratislava). He was an author of an independent implementation of Bitcoin back then (libbitcoin). One day we met in the hackerspace (Progressbar) and he drew a giant tree with many branches and said "I am going to teach you everything there is to know about bitcoin". And we went down every branch. Opcodes, mining, P2P, ...

It was back at the time when Bitcoin was much simpler and it was really possible. 

Amir is amazing.