The success of "Perkinsism" is but a typical instance which is duplicated every twenty years or so by the rapid rise, spread and then rapid decline of some new "craze" in healing, all of which, when investigated are seen to be but new examples of the power of the mental states of faith and imagination upon the physical organism. The well-known "blue glass" craze of about thirty-five years ago gives us another interesting example. General Pleasanton, a well-known and prominent citizen of Philadelphia, announced his discovery that the rays of the sun passing through the medium of blue glass possessed a wonderful therapeutic value. The idea fired the public imagination at once, and the General's book met with a large sale. Everyone, seemingly, began to experiment with the blue glass rays. Windows were fitted with blue glass panes, and the patients sat so that the sun's rays might fall upon them after passing through the blue panes. Wonderful cures were reported from all directions, the results of "Perkinsism" being duplicated in almost every detail. Even cripples reported cures, and many chronic and "incurable" cases were healed almost instantaneously. Bedridden people threw aside their blankets and walked again, after a brief treatment. The interest developed into a veritable "craze," and the glass factories were operated overtime in order to meet the overwhelming demand for blue glass, the price of which rapidly advanced to fifty cents and even a dollar for a small pane, because of the scarcity. It was freely predicted that the days of physicians were over, and that the blue glass was the long-sought-for panacea for all human ills. Suddenly, however, and from no apparent cause, the interest in the matter dropped, and now all that is left of the blue glass craze is the occasional sight of an old blue pane in some window, the owner of which evidently felt disinclined to pay the price of replacing it with a clear pane. Only a few days ago, in an old-fashioned quarter of a large city, the writer saw several panes of the old blue glass in the frame of the window of an old house which had seen better days but which was now used as a cheap tenement house.