"Let the reader be warned accordingly, that whenever he hears a philosopher proclaim any metaphysical opinion with great confidence, or hears him asset that something in metaphysics is obvious, or that some metaphysical problem turns only on confusions of concepts or upon the meanings of words, then he can be quite sure that this man is still infinitely far from philosophical understanding. His views appear to him devoid of difficulties only because he stoutly refuses to see difficulties."