An interesting idea - looking at how the way that fundamental changes in the way people thought in Western Europe from the medieval times onwards led to different ways in which theories of the human sciences began to arise. Foucault looks at three case studies, effectively: natural history, linguistics, and economics (all three labels being anachronistic until the most recent periods) and picks out common features to build a picture of how models of the philosophy of the human place in the world changed, with in depth analysis of concepts such as similarity and representation and what they meant to philosophers.

I found it hard to read (it's very densely packed and expects a lot of knowledge of the subject areas), and also flawed by an over-abundance of rhetoric over analysis.