The story is a fictional, first-person account of meeting a young man who, after being paralyzed, could remember each detail of every moment in his life. He created a new numerical system, where each distinct number could be identified with an image or an identity [aside: this is the actual memory technique used by competitive memory superstars; recent book Moonwalking with Einstein covers the topic in a very accessible fashion]. Unfortunately, as that numerical system abandoned all forms of abstraction, it was incoherent to any other person.
Toward the end of the story, this passage particularly stuck with me.
It was very difficult for him to sleep. To sleep is to be abstracted from the world; Funes, on his back in his cot, in the shadows, imagined every crevice and every molding of the various houses which surrounded him. (I repeat, the least important of his recollections was more minutely precise and more lively than our perception of a physical pleasure or a physical torment)...The bolded passage is a worthy lesson for anyone trying to model social interactions, mathematically or otherwise. A common complaint about economics is that it oversimplifies, reducing complex human motivations to "rationality" or "selfishness." However, humans are so complicated that some reduction is necessary in order to think about their behavior clearly.
Without effort, he had learned English, French, Portuguese, Latin. I suspect, nevertheless, that he was not very capable of thought. To think is to forget a difference, to generalize, to abstract. In the overly replete world of Funes there were nothing but details, almost contiguous details...
A map with a one-to-one scale is simply the terrain; a model which includes every aspect of human psychology is just as incomprehensible as having no model at all. Providing guidance or prediction means abandoning detail and abstracting at one level or another. The relevant question is which details to ignore and which to include, and in this regard economics (especially when informed by insights from psychology) performs pretty well.
Funes reminds me of post-modern theorists (and other critics of social science) who demand ever more detail and less "reductive" ways of understanding human behavior. Laudable goals indeed, but by implication, theory becomes incoherent and the theorist cursed to never sleep.