Page:History of Modern Philosophy (Falckenberg).djvu/551

 PSYCHOLOGY. 529 the burden to be divided) is equal to the sum of all the representations with the exception of the strongest (hence ^= b -- c), and is divided among the individual representa- tions in the inverse ratio of their strength, consequently in such a way that the strongest (the one which most actively and successfully resists arrest) has the least, and the weak- est the most, of it to bear. It may thus come to pass that a representation is entirely driven out of consciousness by two stronger ones, while it is impossible for this to happen to it from a single one, no matter how superior it be. The simplest case of all is when two equally strong representa- tions arc present, in which case each is reduced to the half of its original intensity. The sum of that which remains in consciousness is always equal to the greatest representation. As soon as a representation reaches the zero point of consciousness, or as soon as a new representation (sensation) comes in, the others begin at once to rise or sink. The Mechanics seeks to investigate the laws of these movements of representations ; but we may the more readily pass over its complicated calculations since their precise formulas can never more than very roughly represent the true state of the case, which simply rebels against precision. The rock on which every immanent use of mathematics in psychology must strike, is the impossibility of exactly measuring one representation by another. We may, indeed, declare one stronger than another on the basis of the immediate impres- sion of feeling, but we cannot say how much stronger it is, nor with reason assert that it is twice or half as intense. Herbart's mathematical psychology was wrecked by this insurmountable difficulty. The demand for exactness which it raised, but which it was unable to satisfy with the means at its disposal, has recently been renewed, and has led to assured results in psycho-physics, which works on a different basis and with ingenious methods of meas- urement. Herbart endeavors, as we have seen, to deduce the vari- ous mental activities from the play of representations. Feeling and desire are not something beside represen- tations, are not special faculties of the soul, but results of