 Hume initially distinguishes impressions and ideas in terms of their degree of force and vivacity. Impressions are more forceful and vivacious than ideas. My impression of this ripe tomato’s bright red color is as vivid as anything could be. Last year’s tomatoes were just as vivid when I was looking at them, but now my idea of them is much less vivid than my impressions of the tomato in front of me. Since last year’s tomatoes were the same color, the difference can’t be that they are different shades of red; the difference must lie in the sharpness, clarity, and brightness of my impressions—their force and vivacity. At various times, Hume tries other ways of characterizing the difference between impressions and ideas, but he was never completely satisfied with them. Still, what he says works well enough to give us a handle on the felt differences between impressions and ideas.