William James' stream of consciousness addresses that fundamental fact of our mental world: thinking cannot be stopped. We "think" like we breathe.
James' observation, says Jacques Barzunm
"explains without moralizing what that wonderful self-observer Montaigne found as the chief mark of man: he is [diverse and wandering], a creature of moods and changing views, not a passive recorder of the surrounding world but a congenital 'perspectivist,' and thus easily thrown off in judgment, memory, and purpose--a specialist (as it were) in misunderstanding." Jacques Barzun, A Stroll with William James.