“My proud father suggested “being clever” as an explanation. But I was painfully aware that some people who could not understand the differential could easily do things I found much more difficult. Slowly I began to formulate what I still consider the fundamental fact about learning: Anything is easy if you can assimilate it to your collection of models. If you can’t, anything can be painfully difficult.”
Papert, S. (1981) Mindstorms: Children, Computers and Powerful Ideas. NY: Basic Books. p. vii.