We define boredom as the pain a person feels when he's doing nothing or something irrelevant, instead of something he wants to do but won't, can't, or doesn't dare. Boredom is acute when he knows the other thing and inhibits his action, e.g., out of politeness, embarrassment, fear of punishment or shame. Boredom is chronic if he has repressed the thought of it and no longer is aware of it. A large part of stupidity is just the chronic boredom, for a person can't learn, or be intelligent about, what he's not interested in, when his repressed thoughts are elsewhere.