There is an appearance of charlatanism in the title of my paper. But do not let this mislead you into imagining that I am a dealer in nostrums. I have another request to make. Disabuse yourselves of the possible suspicion that I have pretensions to absolute originality of ideas on the subject, or a desire to combat the ideas of others. Not controversy with theorists of a different way of thinking, but a simple presentation of my own views and teaching, is the object I am aiming at. If, however, my statements—some of which are not unlikely to startle, shock, and horrify you—instil into you a little scepticism with regard to current notions, I for one shall not regret it, and think you ought not to regret it. For scepticism is a wholesome ingredient of the human mind, in fact, the leaven of thought.