The most immediate problem to emerge from Foucault's initial suspension of 'discursive unities' in the last chapter is the difficulty of saying anything about the statements made within disciplines relate to one another. Foucault now begins to address what might seem the most obvious place to start: the divisions of discourse into categories like economics, medicine, or grammar. Although Foucault admits that these groupings of statements seem 'quite obvious' (after all, many historical statements classify themselves under these divisions), this chapter proceeds to show that they are in fact so tricky to define that they cannot be taken for granted at all. Thus, this chapter is partly framed in terms of false starts: Foucault tries out four possible ways to begin specifying coherent groups of statements (by a common object of study, a common style or viewpoint, a constant set of operative concepts, or a common theme), and four times he finds that the relations between the statements are too multiplicitous, shifting, and even dissonant to submit to such organizing principles. A given discourse, even if it can be identified as such, develops as much through sudden irruptions, transformations, contradictions, and differences as it does through constancy or regularity.