This chapter focuses on epistemic virtues, those that bear on thinking and acting well insofar as one's goals are cognitive. It suggests that understanding is fundamentally objectual. Propositional understanding is derivative from objectual understanding. Understanding is surely an epistemic achievement. The question is what sort of achievement it is. Some maintain that understanding is a sort of knowledge. Typically epistemic agents take responsibility for their beliefs, and other epistemic agents hold them responsible for their beliefs. Kvanvig distinguishes between propositional and objectual understanding. The initial acceptability of the positron shows that understanding a subject can involve being committed to the truth of a proposition even if we lack direct evidence for it. The epistemic imperative does not mandate that all epistemically responsible members of an epistemic community agree about everything in their joint purview.