Few people—in fact, very few people indeed—ever realize the priceless value of the ancient counsel: “Know thyself.” It seems so trite¹, so ordinary. It seems so easy to acquire, this knowledge. Does not every one possess it? Can it not be got by simply sitting down in a chair and yielding to a mood? And yet this knowledge is just about as difficult to acquire as a knowledge of Chinese. Certainly nine hundred and ninety-nine people out of a thousand reach the age of sixty before getting the rudiments² of it. The majority of us die in almost complete ignorance of it. And none may be said to master it in all its exciting branches. Why, you can choose any of your friends—the wisest of them—and instantly tell him something glaringly obvious about his own character and actions—and be rewarded for your trouble by an indignantly sincere denial! You had noticed it; all his friends had noticed it. But he had not noticed it. Far from having noticed it, he is convinced that it exists only in your malicious³ imagination. For example, go to a friend whose sense of humour is notoriously imperfect, and say gently to him: “Your sense of humour is imperfect, my friend,” and see how he will receive the information! So much for the rarity of self-knowledge.