sensation at a time, then all he can do is to associate that
particular sensation with some idea. In the case before us he
associates it with the idea of the number two. He cannot conceive of
two objects unless he conceives them as located in two different
places. Sometimes a person does find that the two objects of his
perception are both in the same place, and when he does so he
concludes at once that there is but one object. At other times he
cannot locate them so accurately, and he has no way of finding out the
difference, and since he has associated the sensation with the idea of
two he still continues to call it two. If he is asked to locate the
points on paper he fills out the figure just as he fills out the
blind-spot, and he can draw them in just the same way that he can draw
lines which he thinks he _sees_ with the blind-spot, but which really
he only _infers_.

Any sensation, whether produced by one or by many objects, is one, but
there may be a difference in the quality of a sensation produced by
one object and that of a sensation produced by more than one object.
If this difference is clear and distinct, the person assigns to each
sensation the number he has associated with it. He gives it the name
two when it has the quality he has associated with that idea. But the
qualities of a sensation from which the number of objects producing it
is inferred are not always clear and distinct. The quality of the
sensation must not be confused with any quality of the object. If we
had to depend entirely on the sense of touch and always remained
passive and received sensations only when we were touched by
something, there is no reason why we should not associate the idea of
one with the sensation produced by two objects and the idea of two
with that produced by one object--assuming that we could have any idea
of number under such circumstances. The quality of a sensation from