The point he's stuck on is that the versions of 'read', 'eval', and 'print' in Python aren't the same as the ones in Lisp. In Python, you read a string, eval that string into a value, then print that value. The intermediate representation is a string -- just a bunch of characters. In Lisp, you read a data structure, eval that data structure into another data structure, then print out its form -- nested lists and atoms that you can inspect and manipulate, rather than characters that you need to parse to do anything useful with.