In the second place it is only through the work of these neurologists that psychologists have come to realize how enormously complicated are even those mental functions which have always been regarded as comparatively simple. That the speech function, for example, involves consciousness of sound, of movement, and sometimes of sight, may be recognized immediately, and has been recognized. That our images of things are directly nothing but revived sense impressions of various kinds, visual, auditory, olfactory, and so on, and that our skill in handling things depends upon our experience obtained through running our fingers over them, is also recognized. But that all these images are more than abstractions, that they have a concrete significance even though the subject may not be aware of them, has been recognized only after the study of pathological cases, where, in consequence of peculiar lesions of the brain a dissociation has occurred among those factors which usually work together harmoniously, and where some of them are perhaps entirely lost. It was not until these pathological facts were known that psychology was able to give a definite formulation to certain of its problems. It then became clear that many former problems which took their origin from those popular simplifications, will, judgment, memory, or from the seeming simplicity of ideas and movements, were perfect nonsense, considering the actual complexity of the facts. Now, after having learned how to formulate its problems, psychology can at last hope to understand the phenomena of mental life. The study of the brain has also had an indirect influence upon psychology through the strong impulse which it gave to psychiatry. The knowledge gained in the study of the abnormal mind gave a new insight into the processes of the normal mind. And since psychiatrists most often came into contact with the highly complex mental states, such as emotion, intelligence, self-consciousness, the impulses which they gave to psychology were a happy supplement to those other influences which concerned chiefly sensation and perception. * * * * * During the last decades of the nineteenth century all these buds of a new psychology were--first by Wundt--grafted on the old stem and so united into an harmonious whole. They have rejuvenated the apparently dying tree and brought about a strong new growth. The psychology of the text-book and the lecture room has become a different science. The most conspicuous sign of this new conception of the science of the mind is the establishment of numerous laboratories exclusively devoted to psychological research.