1. Gustav Theodor Fechner 1801 - 1887
German Universities -- Leipzig
Legendary insight – Oct. 22, 1850
Elements of Psychophysics
Founder of Psychophysics
Weber’s Law; Weber Fraction
Methods of Psychophysics – Thresholds (limen);
“just noticeable difference” [jnd]
jnd= dR/R = constant Weber’s Law
What does that formula express in words?
Method of Adjustment
Method of Limits (ascending and descending)
Method of Constant Stimuli

2. Fechner is a curiosity. His eyelids are strangely fringed and he has had a number of holes, square and round, cut, Heaven knows why, in the iris of each eye – and is altogether a bundle of oddities in person and manners. He has forgotten all the details of his “Psychophysik”; and is chiefly interested in theorizing how knots can be tied in endless strings, and how words can be written on the inner side of two slates sealed together G. S. Hall in letter (1879) to William James. Quoted in chapter by Boring on Fechner in The World of Mathematics, Vol. 2.

3. CHAPTER XIII. DISCRIMINATION AND COMPARISON.
James.(1890).Principles Vol.1 pp ‐549
It is surely in some such way as this that Weber's law is to be interpreted, if it ever is. The Fechnerian Maasformel and the conception of it as an ultimate 'psychophysic law' will remain an 'idol of the den,' if ever there was one. Fechner himself indeed was a German Gelehrter of the ideal type, at once simple and shrewd, a mystic and an experimentalist, homely and daring, and as loyal to facts as to his theories. But it would be terrible if even such a dear old man as this could saddle our Science forever with his patient whimsies, and, in a world so full of more nutritious objects of attention, compel all future students to plough through the difficulties, not only of his own works, but of the still drier ones written in his refutation. Those who desire this dreadful literature can find it; it has a 'disciplinary value;' but I will not even enumerate it in a footnote. The only amusing part of it is that Fechner's critics should always feel bound, after smiting his theories hip and thigh and leaving not a stick of them standing, to wind up by saying that nevertheless to him belongs the imperishable glory of the first formulating them and thereby turning psychology into an exact science (!).
"'And everybody praised the duke
Who this great fight did win.'
'But what good came of it at last?'
Quoth little Peterkin.
Why, that I cannot tell, said he,
'But 'twas a famous victory!'"