Modern psychology derives from the application of the scientific method to the study of human nature; it studies objectively the mental mechanisms and motives and their organization; but such "objectivity" includes the capacity to reflect upon experience. To the twentieth century mind this statement seems as simple and convincing as that nature includes mental nature. It is, however, the issue of a long, irregular, and difficult evolution, a slowly accumulated heritage of the ages. We may distinguish three trails1 of interest in man's concern for knowledge about himself; they appear in ancient as clearly as in recent stages. The earliest is a combined religious, cosmic, philosophical expression - a psychosophy, or more simply, soul-lore. By that inclusion, psychology, while a new science, has an ancient history. Soul-lore dominates in early as in primitive reflection; it mingles dramatic invention with inquiry, making myth the antecedent of science. In this approach the study of the mind is incorporated with philosophy. There arises a body of doctrine philosophical in temper but with increasing contributions of psychologically minded philosophers; it characterizes the course of inquiry from Aristotle to Descartes, and from Descartes until the advent of the scientific concept of psychology - a half century ago.

1 As suggested by M. Dessoir, "History of Psychology," The Macmillan Company, N. Y., 1912.

The psychology embodied in it had to be sifted out of the philosophical context by later historians. Stratton has been able to compile a "Physiological Psychology among the Greeks." Gardner Murphy has set contemporary psychology in a perspective of the preceding centuries. Psychology, as we recognize it, had to await a general renaissance of the scientific method and the objective attitude, and to await particularly a more searching biological insight. Besides psychosophy and psychology, there is the practical interest in the affairs of mind, for which the term psychognosis has been suggested. The diagnosis of human character, the judgment of men and motives, ever with a hope of control or prediction of fate, has made the"mental" man the proper study of mankind. It is quickened by the experience with minds disordered seeking cure, no less than with strange experiences demanding explanation, hinting at a hidden order of "psychic" world.

This threefold body of interests is persistent: (a) the place of mind in the world at large; (F) the mechanisms of the mental activities and their association with bodily functions centrally; (c) the varieties of character, the vicissitudes of the human scene, the direction of mental affairs, including the relief of ills that mind is heir to. Gradually the scientific claimant came to be recognized as the legitimate sovereign, absorbing the philosophical and the practical dominions in an inclusive rule.

The historical sequence appears also in terms of concepts of phusis or nature, by virtue of which things come to be and are maintained. How nature is regarded determines all else.

The story of science centers about the nature of nature. It encounters a strong preconception as to what nature should be to conform to human desires or beliefs; it meets with the tendency to imagine forces beyond nature, or miracles setting aside nature; it emerges with an objective, patient study of the environment and the organism. It comes to recognize in nature forces beyond human influence or control, except by the route of comprehension; it comes to recognize man in all respects as part of nature, with affiliations deep and significant with other organisms, no less than with endowments unique but not unrelated to minds of other kinds. Nor can man by any inspiration step out of the scheme of nature, or overcome his limitations, save by that same instrument of understanding that makes the human estate possible.

The history of science thus considered, and psychology centrally, presents a pre-naturalistic or an anti-naturalistic phase and stage; it clings tenaciously to a super-naturalistic intrusion; slowly it emerges to a consistent naturalism. It was by such irregular course that the psychologist became a naturalist. The renaissance of psychology was dependent upon the advent of naturalism. The doctrine of the soul, with its ethical and religious implications and cosmic place, is both pre-natural and anti-natural; the magical-mystical development in primitive and advanced religions goes over to the super-natural, and reappears in so modern a claim as a "meta-psychics." Yet they all fuse from the outset and mingle their products variously and ever with a core of true psychology proceeding upon"natural" observations of the phenomena of the mental world. Naturalizing psychology among the commonwealths of science has proved to be a tortuous process, consummated only in our own generation.

The modern student is interested in understanding how psychology in the scientific temper views and studies the life of the mind; that is the central purpose of this contribution. It can include but a limited survey of the data of the science, selecting by emphasis discoveries that determine principles of interpretation. As already indicated, that issue - the scientific viewpoint - was long delayed through the occupation of the field by concepts and interpretations that to us seem extraneous, irrelevant, crudely speculative, unsupported, and unsound. Their logic seems as alien as their findings. As we go back but a few intellectual generations, we seem to be in a foreign land, where our way of thought can find few points of contact and no sense of illumination, no resting place.

The picture of the mind as we know it to-day is scarcely recognizable; so much is out of focus, so much distorted, so much intruded, so many vital features lacking. An historical retrospect seems like an excursion into a land of errors and phantoms. This may in a measure be true of the antecedents of all science, but applies in larger measure to psychology, because the mind was so open a domain, approachable from so many avenues - a circumstance which accounts equally for the wide reach of its modern applications. All these accumulations of tradition and obstacles to understanding had to be removed or corrected by truer approximations before the heritage that we accept as naturally as steam and electricity and radio came to be ours. The layman of to-day is as familiar with psychology as with physics or chemistry. Man is living in a psychological age; he has developed an intimate interest in interpreting human behavior, as well as the physical resources of the modern world.