That is to say, the details in this act of combination are drawn from
the store of mental recollections to which the growing mind is ever
adding. In other words, the percept arises through a fusion of an actual
sensation with mental representations or "images" of sensation.[6] Every
element of the object that we thus take up in the act of perception, or
put into the percept, as its actual size, distance, and so on, will be
found to make itself known to us through mental images or revivals of
past experiences, such as those we have in handling the object, moving
to and from it, etc. It follows that if this is an essential ingredient
in the act of perception, the process closely resembles an act of
inference; and, indeed, Helmholtz distinctly calls the perception of
distance an unconscious inference or a mechanically performed act of
judgment.

I have hinted that these recovered sensations include the feelings we
experience in connection with muscular activity, as in moving our limbs,
resisting or lifting heavy bodies, and walking to a distant object.
Modern psychology refers the eye's instantaneous recognition of the most
important elements of an object (its essential or "primary" qualities)
to a reinstatement of such simple experiences as these. It is, indeed,
these reproductions which are supposed to constitute the substantial
background of our percepts.

Another thing worth noting with respect to this process of filling up a
sense-impression is that it draws on past sensations of the eye itself.
Thus, when I look at the figure of an acquaintance from behind, my
reproductive visual imagination supplies a representation of the
impressions I am wont to receive when the more interesting aspect of the
object, the front view, is present to my visual sense.[7]