When people have trouble with their emotions – a bout of anxiety or depression, say, or seasonal gloominess - they often want science to pinpoint an … - Thomas Lewis

When trying to fathom an immense, intricate system, drawing direct arrows of causality between micro and macro-components is perilous. Which stock caused the crash of ’29? Which person triggered the outbreak of World War I? Which word of Poe’s “The Rave” suffuses it with an atmosphere of brooding melancholy?

The brain’s dense thicket of interrelationships, like those of history or art, does not yield to the reductivist’s bright blade.

a mood is a state of enhanced readiness to experience a certain emotion. Where an emotion is a single note, clearly struck, hanging for a moment in the still air, a mood is the extended, nearly inaudible echo that follows. Consciousness registers a fading level of activation in the emotion circuits faintly or not at all. And so the provocative events of the day may leave us with emotional responsiveness waiting beneath our notice. If a man spills coffee on himself, his annoyance is relatively short-lived — on the order of minutes. After the conscious feeling is gone, residual activity in the anger circuits lingers. He will pass into an irritable mood — a quickness to anger, the only reflection of the waning activity in those circuits.