The Order of Things: An Archaeology of the Human Sciences (Les mots et les choses: Une archéologie des sciences humaines, 1966) by French philosopher Michel Foucault proposes that every historical period has underlying epistemic assumptions, ways of thinking, which determine what is truth and what is acceptable discourse about a subject, by delineating the origins of biology, economics, and linguistics. The introduction to the origins of the human sciences begins with detailed, forensic analyses and discussion of the complex networks of sightlines, hidden-ness, and representation that exist in the group painting Las Meninas (The Ladies-in-waiting, 1656) by Diego Velázquez. Foucault's application of the analyses shows the structural parallels in the similar developments in perception that occurred in researchers' ways of seeing the subject in the human sciences.
In The Order of Things: An Archaeology of the Human Sciences Foucault wrote that a historical period is characterized by epistemes — ways of thinking about truth and about discourse — which are common to the fields of knowledge, and determine what ideas it is possible to conceptualize and what ideas it is acceptable to affirm as true. That the acceptable ideas change and develop in the course of time, manifested as paradigm shifts of intellectualism, for instance between the periods of Classical antiquity (7th c. BC– AD 5th c.) and Modernity (AD 1500), is support for the thesis that every historical period has underlying epistemic assumptions, ways of thinking that determined what is truth and what is acceptable.
Concerning language: from general grammar to linguistics
Concerning living organisms: from natural history to biology
Concerning money: from the science of wealth to economics
Foucault analyzes three epistemes:
The episteme of the Renaissance, characterized by resemblance and similitude
The episteme of the Classical era, characterized by representation and ordering, identity and difference, as categorization and taxonomy
The episteme of the Modern era, the character of which is the subject of the book
In the Classical-era episteme, the concept of Man was not yet defined, but spoken of.