A certain amount of reverie is good, like a narcotic in discreet doses. It soothes the fever, occasionally high, of the brain at work, and produces in the mind a soft, fresh vapor that corrects the all too angular contours of pure thought, fills up the gaps and intervals here and there, binds them together, and dulls the sharp corners of ideas. But too much reverie submerges and drowns. Thought is the labor of the intellect, reverie it's pleasure. To replace thought with reverie is to confound poison with nourishment.
Victor Hugo, Les Misérables
daydreaming, intellect, reverie, thought