rely a degree of obscuration in the whole
representation, or rather in the representation which actually takes
place.]

As soon as a representation reaches the zero point of consciousness, or as
soon as a new representation (sensation) comes in, the others begin at
once to rise or sink. The Mechanics seeks to investigate the laws of these
movements of representations; but we may the more readily pass over its
complicated calculations since their precise formulas can never more than
very roughly represent the true state of the case, which simply rebels
against precision. The rock on which every immanent use of mathematics
in psychology must strike, is the impossibility of exactly measuring one
representation by another. We may, indeed, declare one stronger than
another on the basis of the immediate impression of feeling, but we cannot
say how much stronger it is, nor with reason assert that it is twice or
half as intense. Herbart's mathematical psychology was wrecked by this
insurmountable difficulty. The demand for exactness which it raised, but
which it was unable to satisfy with the means at its disposal, has recently
been renewed, and has led to assured results in psycho-physics, which works
on a different basis and with ingenious methods of measurement.

Herbart endeavors, as we have seen, to deduce the various mental activities
from the play of representations, Feeling and desire are not something
beside representations, are not special faculties of the soul, but results
of the relations of representations, changing states of representations
arrested and working upward against hindrances. A representation which has
been forced out of consciousness persists as a _tendency or effort_ to
represent, and as such exerts a pressure on the conscious representations.
If a representation is suspended between counteracting forces a feeling
results; desire is the rise of a representation in the face of hindrances,
aversion is hesitation in sinking. If the effort is accompanied by the idea
that its goal is attainable, it is termed will. The character of a man
depends on the fact that definite masses of representations have
become dominant, and by their strength and persistence hold opposing
representations in check or suppress them. The longer the dominant mass of
representations exercises its power, the firmer becomes the habit of acting
in a certain way, the more fixed the will. Herbart's intellectualistic
denial of self-depe