On this account I speak of monistic identity and not of psycho physical parallelism. A thing cannot be parallel with itself. Of course, psychologists of the modern school, when they make use of this term, desire merely to designate a supposed parallelism of phenomena without prejudice either to monism or dualism. Since, however, many central nervous processes are accessible neither to physiological nor to psychological observation, the phenomena ao cessible to us through these two methods of investigation are not in the least parallel, but separated from one anothervery unequally by intermediate processes. Moreover, inasmuch as the dualistic hypothesis is scientifically untenable, it is altogether proper to start out from the hypothesis of identity. It is as clear as day that the same activity in the nervous sys tem of an animal, or even in my own nervous system, observed by myself, fifst by means of physiological methods from without, and second, as re?ecting itself in my consciousness, must appear to me to be totally different, and it would indeed be labor lost to try to convert the physiological into psychological qualities or vice versa. We cannot even convert one psychological quality into another, so far as the reality symbolised by both is concerned; e. G., the tone.