Therefore, as periods in history change, so does a society's existing knowledge structures. Knowledge is inextricably bound to the discourse of a certain period. Discursive formations organize knowledge and in addition are inseparable from knowledge. They determine the kinds of communicative practices societies will engage in. Therefore, they allow some forms of discourse while they prohibit other forms.
Discursive formations are subject to rules.
Speakers express their knowledge through the articulation of utterances that conform to a specific set of rules. Statements and evidence to the contrary were generally denied and silenced. In other words, an author does not hold a superior position to the text but rather is a product of the discourse formation that is present. New York Pantheon, p. 48.