Macbeth, the most awful creation of the poetic mind, is a study every way worthy of those to whom the storms of passion present the frequent cause of mental disease. The historian studies the temper of the mind in its most ardent heats, that he may gain a clue to the causation of human events; the statesman, that he may obtain foreknowledge of tendencies to human action; and the psychologist, for the more beneficent purpose of acquiring that knowledge as the means of alleviating the most terrible of calamities, and of doing that which the terrified physician in this tragedy dared not attempt, of “ministering to the mind diseased.” The philosopher studies the laws of storms, that he may teach the mariner to avoid the destructive circle of their influence; and the physician, whose noble object of study is the human mind, seizes every opportunity of making himself acquainted with the direction and events of its hurricane movements, that he may perchance lead some into a port of safety, or at least that he may assist in the restoration of the torn and shattered bark. But to stand on one side and calmly contemplate the phenomena of human passion, like the chorus in the old Greek drama, is the lot of few. When the elements of human passion are in fierce strife, there is no near standing-place for the foot of science, like the deck of the great steamer which allowed Scoresby to measure the force and speed of the wild Atlantic wave. The vortex of passion tends to draw in all who float near; and tranquil observation of its turmoil can only be made from a standing point more or less remote. On all actual occasions, indeed, it behoves the man whose object of study and of care is the human mind, to observe accurately its phenomena, and to test its springs and sources of action; but it behoves him to accept the testimony of those who have weathered the storm, and also gratefully to appreciate any assistance he may obtain from others who contemplate the same phenomena from different points of view to his own: and there is no one from whom he will derive help of such inestimable value, as from him whose high faculties enables him to contemplate human nature, as it were, from within. The Poet or maker, the same intrinsically with the Seer or gifted observer, is the best guide and helpmate with whom the psychologist can ally himself. He is like the native of a country to whom mountain and stream and every living thing are known, acting as instructor and guide to the naturalist, whose systems and classifications he may hold in slight esteem, but with whom he has a common love and a more personal knowledge for all their objects. Compared with the assistance which the psychologist derives from the true poet, that which he obtains from the metaphysician is as sketchy and indistinct as the theoretical description of a new country might be, given by one who had never been therein, as the description of Australia might be, drawn from the parallel of its climate and latitude with South America or China.