The processes with which the mind perceives the outer world exist only in the abstract. Compared to the study of the body where we have tangible organs that we can dissect to discover a specific purpose, the mind has"mental representations" that serve to prompt the absorption of an outer concept.
But the thought of how much painstaking and meticulous work it takes to explain in words how these mental representations function can be discouraging. Thankfully, the world has Noam Chomsky and his book Modular Approaches to the Study of the Mind.
Chomsky outlines a way to study the cognitive systems that determine how humans understand external reality and does it with a clarity that dissolves whatever hesitation the reader had about even approaching the daunting subject. The more you read, the better you feel about your ability to understand and explain the concepts yourself.