The seasonal nature of belief
Although beliefs seem perfectly stable in daily society, Foucault observes that from a broad perspective, human belief is clearly changing and growing. When more fundamental, paradigmatic assumptions change, a new kind of human society begins to emerge than the one that came in the old way. By taking these changes as a kind of Order he sees a more holistic point of view of what human life is really about.
Linguistics and philosophy
The book addresses the complicated issue of human language, which both communicates meaning and the psyche of the speaker, because the way a person forms their thoughts in communication shows the order of their mind. He treats language as a demonstration of the human mind, and he compares the change of language to the slow, epic cycle of human beliefs, or epistemes, which also change in the same fashion—through time and cultural exchange.
Culture and community
Foucault responds to the ineffable quality of human life by addressing the order of human culture. In any given culture, the history and personality of a culture seem self explanatory, but in Foucault's estimation, culture is a kind of flower that unfurls from a set of shared assumptions, which, as they change, give way to different kinds of cultural flowers. The diversity is obvious, but the commonality is another kind of higher Order.