constituents of experience, very much as material atoms were conceived to
be constituents of natural objects. Sensations became the only objects of
sensation, and ideas the only objects of ideas; so that the material world
was rendered superfluous, and the only scientific problem was now to
construct a universe in terms of analytic psychology. Locke himself did
not go so far, and continued to assign physical causes and physical
objects to some, at least, of his mental units; and indeed sensations and
ideas could not very well have other than physical causes, the existence
of which this new psychology was soon to deny: so that about the origin of
its data it was afterwards compelled to preserve a discreet silence. But
as to their combinations and reappearances, it was able to invoke the
principle of association: a thread on which many shrewd observations may
be strung, but which also, when pressed, appears to be nothing but a
verbal mask for organic habits in matter.

The fact is that there are two sorts of unobjectionable psychology,
neither of which describes a mechanism of disembodied mental states, such
as the followers of Locke developed into modern idealism, to the
confusion of common sense.[8] One unobjectionable sort of psychology is
biological, and studies life from the outside. The other sort, relying on
memory and dramatic imagination, reproduces life from the inside, and is
literary. If the literary psychologist is a man of genius, by the
clearness and range of his memory, by quickness of sympathy and power of
suggestion, he may come very near to the truth of experience, as it has
been or might be unrolled in a human being.[9] The ideas with which Locke
operates are simply high lights picked out by attention in this nebulous
continuum, and identified by names. Ideas, in the original ideal sense of
the word, are indeed the only definite terms which attention can
discriminate and rest upon; but the unity of these units is specious, not
existential. If ideas were not logical or aesthetic essences but