 With some simplification, a cognitive impression reveals its content and that it is kataleptic (cf. Cicero, Academica 2.77–8). For example, when I look at my computer screen while typing this, I may very well have a cognitive impression that this is my computer screen. When I look up and out of the window, I have an impression of a friend walking across campus that is probably non-cognitive. This impression might be true. But since I see her from such a distance, it is pretty surely not cognitive. That is, not all true impressions are cognitive, but all cognitive impressions are true. We should only assent to cognitive impressions, and so in forming our beliefs, hold only those certified beliefs (cf. Brittain 2014 on the Stoic view that assent to cognitive impressions is not compelled).