re is no bitterer foe of the faculty theory than Herbart. His campaign
against it, if not victorious, was yet salutary, and the motives of his
hostility, up to a certain point, entirely justified. Nothing is more
useless than the assurance that what the soul actually does, that it must
also have the power to do. Who disputes this? A faculty explains nothing
so long as the laws under which its functions and its relations to other
faculties remain unexplained. But although the faculty idea serves no
positive end, it cannot be entirely discarded. It marks the boundary where
our ability to reduce one class of psychical phenomena to another ceases.
Herbart's polemic has no force against the moderate and necessary use of
this idea, no matter how much it was in place in view of the impropriety of
a superfluous multiplication of the faculties of the soul. The realization
of the ideal of psychology, the reduction of the complex phenomena of
mental life to the smallest possible number of simple elements, is limited
by the heterogeneity of the original phenomena, knowing, feeling, willing,
which wholly resists derivation from the combination of sensations. That
which blinded Herbart to these limitations was that tendency toward unity,
which, as a metaphysician and moral philosopher, he had all too willfully
suppressed, and which now took revenge for this infringement of its rights
by misleading the psychologist to an exaggeration which had important
consequences. Nevertheless his unsuccessful attempt remains interesting and
worthy of gratitude.

The discovery of the laws which govern the interaction of the psychical
elements is the task of a _statics and a mechanics_ of representations. The
former investigates the equilibrium or the settled final state; the latter,
the change, _i.e._ the movements of representations. These names of
themselves betray Herbart's conviction that mathematics can and must be
applied to psychology. The bright hopes, however, which Herbart formed for
the attempt at a mathematical psychology, were fulfilled neither in his own
endeavors nor in those of his pupils, although, as Lotze remarks, it would
be asserting too much to say that the most general formulas which he set up
contradict experience.--The unity of the soul forces representations to act
on one another. Disparate representations, those, that is, which belong
to different representative series, as the visual image of a rose and the
auditory ima