The only absolutely essential reference book for this study is Ploetz's "Epitome of Universal History." To make this fad interesting, the mere commitment to memory of facts and dates will not suffice. Items of history thus acquired will inevitably fade. The conscientious but ill-advised student who attempts to commit the "Epitome" to memory will fall by the way-side. Time is not wasted in dwelling sufficiently long on one subject to feel a sense of ownership in it, and there is opportunity for the exercise of individual ingenuity in devising means to accomplish this end. If one has the knack, for example, of writing nonsense verse (and this is a talent all too easy of cultivation) it will aid him in fixing by rhyme names and dates otherwise difficult to master, thus: "Ten sixty-six is a date you must fix;" or "Drake was not late in fifteen eighty-eight." The study of music, history, trees, flowers, or birds doubtless seems of trivial interest to one who occupies his leisure hours with such weighty problems as figuring out how rich he would have been to-day if he had bought Bell Telephone at 15, but such study is far more restful, and in the long run quite as useful for the over-busy man. It is not necessary to devote an enormous amount of time to such pursuits. One has only to purchase Miss Huntington's "Studies of Trees in Winter" and learn the trees in his own doorway, or upon his street, to awaken an interest that will serve him in good stead upon a railroad journey, or during an otherwise monotonous sojourn in the country. A walk around the block before dinner with such an object in view is more restful than pondering in one's easy-chair over the fluctuations of the stock market, and the man who is "too busy" for such mental relaxation is paving the way for ultimate, perhaps early, breakdown. Once started on the trees, the man who did not even know that their buds were visible in the winter, after absorbing the contents of the popular tree-books may find himself looking for something more elaborate. He may even look forward to his next western trip with pleasure instead of disgust, now that he anticipates seeing at close hand the eucalyptus, the Monterey cypress, and the _pinus ponderosa_. Courtney says "to all this will undoubtedly be objected the plea of lack of time. The answer to arguments formed on such flimsy basis is that all the time which is spent in preparing one's self as a candidate for a sanitarium is like the proverbial edged tool in the hands of children and fools."