The confidence that opened this chapter wasn't arrogance. It was earned, by real results on real problems.

The mistake was assuming small wins predicted larger ones. The problems that worked turned out to be a narrow category: closed, formal, tidy. The moment you stepped outside that category, into language, into common sense, into the ordinary mess of the world, the approach collapsed.

The field would return. But it would take a different road. And that took time.