of which to make it
up. This object is a concretion of my perceptions in space, so that the
redness, hardness, sweetness, and roundness of the apple are all fused
together in my practical regard and given one local habitation and one
name.

[Sidenote: Universals are concretions in discourse.]

This kind of synthesis, this superposition and mixture of images into
notions of physical objects, is not, however, the only kind to which
perceptions are subject. They fall together by virtue of their
qualitative identity even before their spatial superposition; for in
order to be known as repeatedly simultaneous, and associable by
contiguity, they must be associated by similarity and known as
individually repeated. The various recurrences of a sensation must be
recognised as recurrences, and this implies the collection of sensations
into classes of similars and the apperception of a common nature in
several data. Now the more frequent a perception is the harder it will
be to discriminate in memory its past occurrences from one another, and
yet the more readily will its present recurrence be recognised as
familiar. The perception in sense will consequently be received as a
repetition not of any single earlier sensation but of a familiar and
generic experience. This experience, a spontaneous reconstruction based
on all previous sensations of that kind, will be the one habitual _idea_
with which recurring sensations will be henceforth identified. Such a
living concretion of similars succeeding one another in time, is the
idea of a nature or quality, the universal falsely supposed to be an
abstraction from physical objects, which in truth are conceived by
putting together these very ideas into a spatial and permanent system.

Here we have, if I am not mistaken, the origin of the two terms most
prominent in human knowledge, ideas and things. Two methods of
conception divide our attention in common life; science and philosophy
develop both, although often with an unjustifiable bias in favour of one
or the other. They are nothing but the old principles of Aristotelian
psychology, association by similarity and association by contiguity.
Only now, after logicians have exhausted their ingenuity in criticising
them and psychologists in applying them, we may go back of the
traditional position and apply the ancient principles at a deeper stage
of mental life.

[Sidenote: Similar reactions, merged in one habit of reproduction, yield
an