But in recent years a complete change can be traced in our science.  Experiments which refer to these individual differences themselves have been carried on by means of the psychological laboratory, at first reluctantly and in tentative forms, but within the last ten years the movement has made rapid progress.  To-day we have a psychology of individual variations from the point of view of the psychological laboratory.[1] This development of schemes to compare the differences between the individuals by the methods of experimental science was after all the most important advance toward the practical application of psychology.  The study of the individual differences itself is not applied psychology, but it is the presupposition without which applied psychology would have remained a phantom.

II

THE DEMANDS OF PRACTICAL LIFE

While in this way the progress of psychology itself and the development of the psychology of individual differences favored the growth of applied psychology, there arose at the same time an increasing demand in the midst of practical life.  Especially the teachers and the physicians, later the lawyers as well, looked for help from exact psychology.  The science of education and instruction had always had some contact with the science of the mind, as the pedagogues could never forget that the mental development of the child has to stand in the centre of educational thought.  For a long while pedagogy was still leaning on a philosophical psychology, after that old-fashioned study of the soul had been given up in psychological quarters.  At last, in the days of progressive experimental psychology, the time came when the teachers under the pressure of their new needs began to inquire how far the modern laboratory could aid them in the classroom.  The pedagogical psychology of memory, of attention, of will, and of intellect was systematically worked up by men with practical school interests.  We may notice in the movement a slow but most important shifting.  At first the results of theoretical psychology were simply transplanted into the pedagogical field.  Experiments which were carried on in the interest of pure theoretical science were made practical use of, but their application remained a mere chance by-product.  Only slowly did the pedagogical problems themselves begin to determine the experimental investigation.  The methods of laboratory psychology were applied for the solving of those problems which originated in the school experience, and only when this point was reached could a truly experimental pedagogy be built on a psychological foundation.  We stand in the midst of this vigorous and healthy movement, which has had a stimulating effect on theoretical psychology itself.