It would be impossible to accept naturalism itself if we really and consistently believed naturalism. For naturalism is a system of thought. But for naturalism all thoughts are mere events with irrational causes. It is, to me at any rate, impossible to regard the thoughts which make up naturalism in that way and, at the same time, regard them as a real insight into external reality...If it is true, then we can know no truths. It cuts its own throat.