of classification is assigned to the following considerations: (1)
Distinctions between associations according to logical relations are
extremely difficult to define; in many cases there is room for
difference of opinion as to the proper place for an association, and
thus the application of a logical scheme depends largely upon the
personal equation of the observer; that even experienced observers
cannot, in all cases, agree in placing an association is shown by
Aschaffenburg's criticisms of the opinions of other observers on this
point.[2] (2) Logical distinctions do not bring out clearly the
differences between the reactions of normal subjects and those of
insane subjects; logically, the reaction _bath--ink_, which was given
by a patient, might be placed in the class with the reaction
_bath--water_, although there is an obvious difference between the two
reactions. (3) Many of the reactions given by insane subjects possess
no obvious logical value whatever; but since any combination of ideas
may represent a relationship, either real or imagined, it would be
arbitrary to characterize such a reaction as incoherent.

[Footnote 1: Experimentelle Studien uber Association. Psychologische
Arbeiten, Vol. I, p. 209; Vol. II, p. 1; Vol. IV, p. 235.]

[Footnote 2: Loc. cit, Vol. 1, pp. 226-227.]

The criterion of values which is used in this study is an empirical
one. As has already been explained (p. 8), every word contained in the
frequency tables possesses a value of at least 0.1 per cent, and other
words have a zero value. With the aid of our method the difficulty of
classifying the reactions quoted above is obviated, as it is necessary
only to refer to the table to find their proper values: the value of
the reaction _bath--water_ is 33.9 per cent, while that of the