es an indirect contiguity between the two things, a {396}
sort of contiguity bridge between them. One thing has the parts or
characteristics, A B X Y, and the similar thing has the parts or
characteristics, C D X Y; and thus X Y, when seen in the second thing,
call up A B, with which they are contiguous in the first thing.

A stranger reminds me of my friend because something in the stranger's
face or manner has been met with before in my friend; it has been
contiguous with my friend, and recalls him by virtue of this
contiguity. The stranger, as a whole individual, has never been
contiguous with my friend, but some characteristic of the stranger has
been thus contiguous. In association by similarity, it is not the
whole present object that arouses recall of the similar object, but
some _part_ of the present object. This kind of association is
important in thinking, since it brings together facts from different
past experiences, and thus assembles data that may be applied to a new
problem. If every new object or situation could only be taken as a
whole, it could not remind me of anything previously met; and I should
be like an inexperienced child in the presence of each new problem;
but, taken part by part, the novel situation has been met with before,
and can be handled in the light of past experience.

Exactly what there is in common between two similar faces or other
objects cannot always be clearly made out; but the common
characteristic is there, even if not consciously isolated, and acts as
an effective stimulus to recall.

Association by Contiguity

This reduction of all the laws of association to one great law was no
mean achievement; and the law of association by contiguity in
experience holds good. If one thing recalls another to your mind, you
can be sure that the two {397} have been contiguous in your
experience, either as wholes or piecemeal. For two things to become
associated, they must be experienced together.

Yes, the law holds good, when thus stated--but notice that the
statement is virtually negative. It says, in effect, that two things
do _not_ become associated _unless_ they are contiguous in experience.
If it were turned about to read that two things do become associated
if they are contiguous in experience, it would no longer be a true
law, for the exceptions would then be extremely numerous.

The memory and testimony experiments have brought many exceptions to
light. Show a person twent