Commercial life as a whole finds its contact with psychology, of course, not only in the problem of how to secure the best mental effect. Those other questions which we have discussed essentially with reference to factory life and industrial concerns, namely, how the best man and the best work are to be secured, recur in the circle of commercial endeavors. It seems, indeed, most desirable to devise psychological tests by which the ability to be a successful salesman or saleswoman may be determined at an early stage. The lamentable shifting of the employees in all commercial spheres, with its injurious social consequences, would then be unnecessary, and both employers and employees would profit. Moreover, like the selection of the men, the means of securing the most satisfactory work from them, has also so far been left entirely to common sense. Commercial work stands under an abundance of varying conditions, and each may have influences the isolated effects of which are not known, because they have not been studied in that systematic form which only the experiment can establish. The popular literature on this whole group of subjects is extensive, and in its expansion corresponds to the widespread demand for real information and advice to the salesman. But hardly any part of the literature in the borderland regions of economics is so disappointing in its vagueness, emptiness, and helplessness. Experimental psychology has nothing with which to replace it to-day, but it can at least show the direction from which decisive help may be expected in future. XXIV THE FUTURE DEVELOPMENT OF ECONOMIC PSYCHOLOGY