intelligence

What is intelligence, anyway? It is only a word that people use to name those unknown processes with which our brains solve problems we call hard. But whenever you learn a skill yourself, you are less impressed or mystified when other people do the same.

This is why the meaning of "intelligence" seems so elusive: It describes not some definite thing but only the momentary horizon of our ignorance about how minds might work.

Marvin Minsky, AI researcher