ABSTRACT
Reports about that illness in the English-language literature on G. T. Fechner are fragmentary. Fechner’s scientific bent was so strong that, after his illness, he described how some of his own visual experiences differed from those of others viewing the same visual stimulus. Fechner introduced into his purely verbal arguments a distinction that mathematicians made from antiquity, namely, the distinction between multiplication and addition. In the theoretical context, Fechner offered his “Parallel Law” to E. H. Weber’s Law. Following a survey of how Fechner, as a professor of physics at the University of Leipzig, interacted with the Weber brothers, an account of his famous illness is given that is based on the four self-reports he left us describing his experiences. The chapter concludes with a discussion of Fechner’s controversial “Parallel Law” that, nevertheless, ushered in his distinction between “outer psychophysics” and “inner psychophysics”.
