as the former owes
its generality not to its being the sign of an abstract or general line,
but of all particular right lines that may possibly exist, so the latter
must be thought to derive its generality from the same cause, namely,
the various particular lines which it indifferently denotes." *

* Introduction to "A Treatise concerning the Principles of
Human Knowledge," paragraphs 10, 11, and 12.

Berkeley's view in the above passage, which is essentially the same as
Hume's, does not wholly agree with modern psychology, although it comes
nearer to agreement than does the view of those who believe that there
are in the mind single contents which can be called abstract ideas. The
way in which Berkeley's view is inadequate is chiefly in the fact that
images are as a rule not of one definite prototype, but of a number of
related similar prototypes. On this subject Semon has written well.
In "Die Mneme," pp. 217 ff., discussing the effect of repeated similar
stimuli in producing and modifying our images, he says: "We choose a
case of mnemic excitement whose existence we can perceive for ourselves
by introspection, and seek to ekphore the bodily picture of our nearest
relation in his absence, and have thus a pure mnemic excitement before
us. At first it may seem to us that a determinate quite concrete picture
becomes manifest in us, but just when we are concerned with a person
with whom we are in constant contact, we shall find that the ekphored
picture has something so to speak generalized. It is something like
those American photographs which seek to display what is general about a
type by combining a great number of photographs of different heads over
each other on one plate. In our opinion, the generalizations happen by
the homophonic working of different pictures of the same face which we
have come across in the most different conditions and situations, once
pale, once reddened, once cheerful, once earnest, once in this
light, and once in that. As soon as we do not let the whole series
of repetitions resound in us uniformly, but give our attention to one
particular moment out of the many... this particular mnemic stimulus at
once overbalances its simultaneously roused predecessors and successors,
and we perceive the face in question with concrete definiteness in that
particular situation." A little later he says: "The result is--at least
in man, but probably also in the higher animals--the development of a