meters or inches, and for pounds or ounces. Taking up these hints, Fechner ransacked the choir of heaven and the furniture of earth to see if this general relation which, with characteristic modesty, he called Weber's law, did not hold true for all kinds of impressions, for sounds, for colors, lights, temperature, short intervals of time; he even questioned if it did not hold for our feelings; in short, if it was not a fundamental law of human activity. With characteristic thoroughness he launched forth into new seas of experimentation. He tells us:
For several years I considered it a daily task to experiment about an hour for the purpose of testing Weber's Law and for elaborating new methods of research.
This daily task consisted in "hefting" and comparing pairs of small weights, in analyzing out the multifarious factors involved in judgments of likeness or difference and in noting the results. In so far as Weber's law is concerned it can not be said that the outcome of this vast accumulation of data is decisive, but so far as regards the working out of psychophysical methods of measurement, the experimentation was extraordinarily fertile. For the development of the Fechnerian methods meant that Fechner had founded a new science and reared somewhat of its superstructure in a domain whose only uniformity seemed boundless variability, and that later psychology has failed to find either the universality or the exactness in Weber's law which Fechner hoped to show is assuredly a matter of small importance in comparison with the birth of a quantitative psychology.
In the latter part of the treatise Fechner passes over to discuss what he calls "Inner Psychophysics," and here we strike a mine of acute and subtle psychological observations on sleep and dreams, on hallucination and illusions, on memory and after-images from which most writers of text-books and no small number of investigators up to the present day have "lifted" no small amount of ore. Taken as a whole, from the first remarkable chapter, remarkable at that day, on the conservation of force, through the mathematical treatment of methods of "mental measurement" up to the final discussion of psychophysical motion, the "Psychophysik" is a work which in the library of science one need not fear to place on the same shelf with the "Origin of Species."
If the importance of a work is to be measured by the number and repute of its critics, Fechner had no longer any cause for feeling that his theories were of no significance to the learned world, for among the cloud of witnesses who rose up to testify against the "Psychophysik" we find the names of v. Helmholtz, Hering and Mach, and later Wundt and G. E. Müller of Göttingen. Indeed so acute and penetrating was the criticism of Müller, that Fechner was obliged to defend himself in a new work entitled "Revision of the Main Points of Psychophysics." Later on he wrote a sort of omnibus reply to all his critics and up to the
