Just think what you could do if you had all the pieces of information that you have studied always that close at hand. Allow me to give you another example. And his work reflected that higher level of refinement. Compare it to the computer here. Textbooks,reports,databooks,etc are to memory as a typwriter is to the computer.
Memory is partly gift and mostly practice.
So forcing your children to do memorization is the better part of giving this gift to your student. All the performances were held in that one chamber - the musicians were not allowed to write it down or perform any part of it elsewhere. Soon after Mozart attended, the music was being played under his direction elsewhere. The Pope of the time called him in to call him to task. The Pope had pity - no one had thought to warn a child.