As for the "solitary confinement of the mind," my theory is that solipsism, like other absurdities of the professional philosopher, is a product of too much time wasted in library stacks between the covers of a book, in smoke-filled coffeehouses (bad for brains) and conversation-clogged seminars. To refute the solipsist or the metaphysical idealist all that you have to do is take him out and throw a rock at his head: if he ducks he's a liar. His logic may be airtight but his argument, far from revealing the delusions of living experience, only exposes the limitations of logic.

p. 121 - The Journey Home (1977)