Comparison is not a frivolity. It is, on the contrary, the primary business of the brain. Some eighteenth-century philosophers spoke of the human mind as a tabula rasa, a “blank slate” on which sense impressions are recorded, compared, and grouped. Now we’re more likely to speak of the mind as a computer “storing” and “processing” “data.” What both metaphors acknowledge is that comparison is the basis of all learning and all reasoning.

Janet Burroway, Writing Fiction, Tenth Edit…, loc. 604