Dehaene's First Law
Every successful human invention such as arithmetic or the alphabet has a "neuronal niche"—a set of cerebral processors that evolved for a distinct purpose, but can be recycled to implement the new function.
The difficulty of learning a new concept or technique is directly related to the amount of recycling needed—the distance between the evolutionary older function and the new one.
When the old and the new functions are closely related (isomorphic), an evolutionary old cerebral processor can provide a fast, unconscious and unexpected solution to a recent cultural problem—this is what we call
Dehaene's Second Law
The confusability of two ideas, however abstract, is a direct function of the overlap in their neuronal codes.