FECHNER, GUSTAV THEODOR German experimental psychologist, was born on April 19, 18o1 at Gross Sarchen, Lower Lusatia, where his father was pastor. He was educated at Dresden and Leipzig, where he spent the rest of his life. In 1834 he was appointed professor of physics, but, because of an affection of the eyes, turned in 1843 to the study of mind and the relations between body and mind. He died at Leipzig on Nov. 18, 188 7. His chief works are: Das Biichlein vom Leben nach dem Tode (1836, Eng. trs. 1882) ; Nanna, oder uber das Seelenleben der Pflanzen (1848) ; Zendavesta, oder fiber die Dinge des Himmels and des Jenseits (1851) ; Uber die physikalische and philosophische Atomenlehre ; Elemente der Psychophysik (186o) ; V orschule der Asthetik (1876) ; Die Tagesansicht gegen iuber der Nachtansicht (1879). Besides chemical and physical papers, he wrote poems and humorous pieces, such as the V er gleichende Anatomie der Engel (1825), written under the pseudo nym of "Dr. Mises." Fechner's epoch-making work was his Elemente der Psycho physik (186o). He starts from the Spinozistic thought that bodily facts and conscious facts, though not reducible one to the other, are different sides of one reality. His originality lies in trying to discover an exact mathematical relation between them. The most famous outcome of his inquiries is the law known as Weber's or Fechner's law which may be expressed as follows:—"In order that the intensity of a sensation may increase in arithmetical progression, the stimulus must increase in geometrical pro gression." Though holding good within certain limits only, the law has proved immensely useful. Unfortunately, from the tenable theory that the intensity of a sensation increases by definite additions of stimulus, Fechner was led on to postulate a unit of sensation, so that any sensations might be regarded as composed of n units. Sensations, he argued, being representable by numbers, psychology may become an "exact" science. His general formula for getting at the number of units in any sensation is 1= C log. S, where I stands for the sensation, S for the stimulus numerically estimated, and C for a constant that must be sep arately determined by experiment in each particular order of sensi 'The liqueur is said to have been made by the monks as far back as 151o; since the Revolution it has been produced by a secular company. The familiar legend D.O.M. (Deo Optimo Maximo) on the bottles preserves the memory of its original makers.
bility. The fundamental mistake in this theory lies in the fact that though stimuli are composite, sensations are not. The idea of the exact measurement of sensation, however, has been a fruitful one, and mainly through his influence on Wundt, Fechner was the father of that laboratory psychology which investigates human faculties with scientific apparatus. His general philosophy conceives the world as highly animistic, even plants and the stars being animated ; God, the soul of the universe, has an existence analogous to men, and natural laws are just the modes of the unfolding of God's perfection. Fechner was remotely a disciple of Schelling, learnt much from Herbart and Weisse, and decidedly rejected Hegel and the monadism of Lotze.