How did Foucault analyze the knowledge forms in three different historical periods in western history?

Foucault analyzed the forms of knowledge in three different historical periods in western history. In his view, there were three different types of knowledge during the Renaissance, classical and modern. During the Renaissance, the relationship between words and things was based on the principle of "imitation". In the classical era initiated by the Enlightenment, this relationship was based on the principle of "similarities and differences" and became the basis of grammar, natural history and economic analysis. After the world enters the modern era, people "return to language", and under the influence of the cognitive model of modern humanities, they find that language is a "rude existence". Therefore, in contemporary times, the authenticity of language reflecting the world and existence is increasingly questioned and criticized.