On The Soul
The reason of the last characteristic is as follows. Perception
(1) of the special objects of sense is never in error or admits the
least possible amount of falsehood. (2) That of the concomitance of
the objects concomitant with the sensible qualities comes next: in
this case certainly we may be deceived; for while the perception
that there is white before us cannot be false, the perception that
what is white is this or that may be false. (3) Third comes the
perception of the universal attributes which accompany the concomitant
objects to which the special sensibles attach (I mean e.g. of movement
and magnitude); it is in respect of these that the greatest amount
of sense-illusion is possible.
The motion which is due to the activity of sense in these three
modes of its exercise will differ from the activity of sense; (1)
the first kind of derived motion is free from error while the
sensation is present; (2) and (3) the others may be erroneous
whether it is present or absent, especially when the object of
perception is far off. If then imagination presents no other
features than those enumerated and is what we have described, then
imagination must be a movement resulting from an actual exercise of
a power of sense.
As sight is the most highly developed sense, the name Phantasia
(imagination) has been formed from Phaos (light) because it is not
possible to see without light.
And because imaginations remain in the organs of sense and
resemble sensations, animals in their actions are largely guided by
them, some (i.e. the brutes) because of the non-existence in them of
mind, others (i.e. men) because of the temporary eclipse in them of
mind by feeling or disease or sleep.
About imagination, what it is and why it exists, let so much