darkness destroys the sight, and in the case of smell excess of
strength whether in the direction of sweetness or bitterness is
destructive.) This shows that the sense is a ratio.
That is also why the objects of sense are (1) pleasant when the
sensible extremes such as acid or sweet or salt being pure and unmixed
are brought into the proper ratio; then they are pleasant: and in
general what is blended is more pleasant than the sharp or the flat
alone; or, to touch, that which is capable of being either warmed or
chilled: the sense and the ratio are identical: while (2) in excess
the sensible extremes are painful or destructive.
Each sense then is relative to its particular group of sensible
qualities: it is found in a sense-organ as such and discriminates
the differences which exist within that group; e.g. sight
discriminates white and black, taste sweet and bitter, and so in all
cases. Since we also discriminate white from sweet, and indeed each
sensible quality from every other, with what do we perceive that
they are different? It must be by sense; for what is before us is
sensible objects. (Hence it is also obvious that the flesh cannot be
the ultimate sense-organ: if it were, the discriminating power could
not do its work without immediate contact with the object.)
Therefore (1) discrimination between white and sweet cannot be
effected by two agencies which remain separate; both the qualities
discriminated must be present to something that is one and single.
On any other supposition even if I perceived sweet and you perceived
white, the difference between them would be apparent. What says that
two things are different must be one; for sweet is different from
white. Therefore what asserts this difference must be
self-identical, and as what asserts, so also what thinks or perceives.
That it is not possible by means of two agencies which remain separate
to discriminate two objects which are separate, is therefore
obvious; and that (it is not possible to do this in separate movements
of time may be seen' if we look at it as follows. For as what
asserts the difference between the good and the bad is one and the
same, so also the time at which it asserts the one to be different and
the other to be different is not accidental to the assertion (as it is
for instance when I now assert a difference but do not assert that
there is now a difference); it asserts thus-both now and that the
objects are different now; the objects therefore must be present at
one and the same moment. Both the discriminating power and the time of
its exercise must be one and undivided.
But, it may be objected, it is impossible that what is
self-identical should be moved at me and the same time with contrary
movements in so far as it is undivided, and in an undivided moment
of time. For if what is sweet be the quality perceived, it moves the
sense or thought in this determinate way, while what is bitter moves
it in a contrary way, and what is white in a different way. Is it
the case then that what discriminates, though both numerically one and
indivisible, is at the same time divided in its being? In one sense,
it is what is divided that perceives two separate objects at once, but
in another sense it does so qua undivided; for it is divisible in
its being but spatially and numerically undivided. is not this
impossible? For while it is true that what is self-identical and
undivided may be both contraries at once potentially, it cannot be
self-identical in its being-it must lose its unity by being put into
activity. It is not possible to be at once white and black, and
therefore it must also be impossible for a thing to be affected at one
and the same moment by the forms of both, assuming it to be the case
that sensation and thinking are properly so described.
The answer is that just as what is called a 'point' is, as being
at once one and two, properly said to be divisible, so here, that
which discriminates is qua undivided one, and active in a single
moment of time, while so far forth as it is divisible it twice over
uses the same dot at one and the same time. So far forth then as it
takes the limit as two' it discriminates two separate objects with
what in a sense is divided: while so far as it takes it as one, it
does so with what is one and occupies in its activity a single
moment of time.
About the principle in virtue of which we say that animals are
percipient, let this discussion suffice.
3
There are two distinctive peculiarities by reference to which we
characterize the soul (1) local movement and (2) thinking,
discriminating, and perceiving. Thinking both speculative and
practical is regarded as akin to a form of perceiving; for in the
one as well as the other the soul discriminates and is cognizant of
something which is. Indeed the ancients go so far as to identify
thinking and perceiving; e.g. Empedocles says 'For 'tis in respect
of what is present that man's wit is increased', and again 'Whence
it befalls them from time to time to think diverse thoughts', and
Homer's phrase 'For suchlike is man's mind' means the same. They all
look upon thinking as a bodily process like perceiving, and hold
that like is known as well as perceived by like, as I explained at the
beginning of our discussion. Yet they ought at the same time to have
accounted for error also; for it is more intimately connected with
animal existence and the soul continues longer in the state of error
than in that of truth. They cannot escape the dilemma: either (1)
whatever seems is true (and there are some who accept this) or (2)
error is contact with the unlike; for that is the opposite of the
knowing of like by like.
But it is a received principle that error as well as knowledge in
respect to contraries is one and the same.
That perceiving and practical thinking are not identical is
therefore obvious; for the former is universal in the animal world,
the latter is found in only a small division of it. Further,
speculative thinking is also distinct from perceiving-I mean that in
which we find rightness and wrongness-rightness in prudence,
knowledge, true opinion, wrongness in their opposites; for
perception of the special objects of sense is always free from
error, and is found in all animals, while it is possible to think
falsely as well as truly, and thought is found only where there is
discourse of reason as well as sensibility. For imagination is
different from either perceiving or discursive thinking, though it
is not found without sensation, or judgement without it. That this
activity is not the same kind of thinking as judgement is obvious. For
imagining lies within our own power whenever we wish (e.g. we can call
up a picture, as in the practice of mnemonics by the use of mental
images), but in forming opinions we are not free: we cannot escape the
alternative of falsehood or truth. Further, when we think something to
be fearful or threatening, emo
tion is immediately produced, and so too
with what is encouraging; but when we merely imagine we remain as
unaffected as persons who are looking at a painting of some dreadful
or encouraging scene. Again within the field of judgement itself we
find varieties, knowledge, opinion, prudence, and their opposites;
of the differences between these I must speak elsewhere.
Thinking is different from perceiving and is held to be in part
imagination, in part judgement: we must therefore first mark off the
sphere of imagination and then speak of judgement. If then imagination
is that in virtue of which an image arises for us, excluding
metaphorical uses of the term, is it a single faculty or disposition
relative to images, in virtue of which we discriminate and are
either in error or not? The faculties in virtue of which we do this
are sense, opinion, science, intelligence.
That imagination is not sense is clear from the following
considerations: Sense is either a faculty or an activity, e.g. sight
or seeing: imagination takes place in the absence of both, as e.g.
in dreams. (Again, sense is always present, imagination not. If actual
imagination and actual sensation were the same, imagination would be
found in all the brutes: this is held not to be the case; e.g. it is
not found in ants or bees or grubs. (Again, sensations are always
true, imaginations are for the most part false. (Once more, even in
ordinary speech, we do not, when sense functions precisely with regard
to its object, say that we imagine it to be a man, but rather when
there is some failure of accuracy in its exercise. And as we were
saying before, visions appear to us even when our eyes are shut.
Neither is imagination any of the things that are never in error: e.g.
knowledge or intelligence; for imagination may be false.
It remains therefore to see if it is opinion, for opinion may be
either true or false.
But opinion involves belief (for without belief in what we opine
we cannot have an opinion), and in the brutes though we often find
imagination we never find belief. Further, every opinion is
accompanied by belief, belief by conviction, and conviction by
discourse of reason: while there are some of the brutes in which we
find imagination, without discourse of reason. It is clear then that
imagination cannot, again, be (1) opinion plus sensation, or (2)
opinion mediated by sensation, or (3) a blend of opinion and
sensation; this is impossible both for these reasons and because the
content of the supposed opinion cannot be different from that of the
sensation (I mean that imagination must be the blending of the
perception of white with the opinion that it is white: it could
scarcely be a blend of the opinion that it is good with the perception
that it is white): to imagine is therefore (on this view) identical
with the thinking of exactly the same as what one in the strictest
sense perceives. But what we imagine is sometimes false though our
contemporaneous judgement about it is true; e.g. we imagine the sun to
be a foot in diameter though we are convinced that it is larger than
the inhabited part of the earth, and the following dilemma presents
itself. Either (a while the fact has not changed and the (observer has
neither forgotten nor lost belief in the true opinion which he had,
that opinion has disappeared, or (b) if he retains it then his opinion
is at once true and false. A true opinion, however, becomes false only
when the fact alters without being noticed.
Imagination is therefore neither any one of the states enumerated,
nor compounded out of them.
But since when one thing has been set in motion another thing may be
moved by it, and imagination is held to be a movement and to be
impossible without sensation, i.e. to occur in beings that are
percipient and to have for its content what can be perceived, and
since movement may be produced by actual sensation and that movement
is necessarily similar in character to the sensation itself, this
movement must be (1) necessarily (a) incapable of existing apart
from sensation, (b) incapable of existing except when we perceive,
(such that in virtue of its possession that in which it is found may
present various phenomena both active and passive, and (such that it
may be either true or false.
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
suffice.
4
Turning now to the part of the soul with which the soul knows and
thinks (whether this is separable from the others in definition
only, or spatially as well) we have to inquire (1) what differentiates
this part, and (2) how thinking can take place.
If thinking is like perceiving, it must be either a process in which
the soul is acted upon by what is capable of being thought, or a
process different from but analogous to that. The thinking part of the
soul must therefore be, while impassible, capable of receiving the
form of an object; that is, must be potentially identical in character
with its object without being the object. Mind must be related to what
is thinkable, as sense is to what is sensible.
Therefore, since everything is a possible object of thought, mind in
order, as Anaxagoras says, to dominate, that is, to know, must be pure
&n
bsp; from all admixture; for the co-presence of what is alien to its nature
is a hindrance and a block: it follows that it too, like the sensitive
part, can have no nature of its own, other than that of having a
certain capacity. Thus that in the soul which is called mind (by
mind I mean that whereby the soul thinks and judges) is, before it
thinks, not actually any real thing. For this reason it cannot
reasonably be regarded as blended with the body: if so, it would
acquire some quality, e.g. warmth or cold, or even have an organ
like the sensitive faculty: as it is, it has none. It was a good
idea to call the soul 'the place of forms', though (1) this
description holds only of the intellective soul, and (2) even this
is the forms only potentially, not actually.
Observation of the sense-organs and their employment reveals a
distinction between the impassibility of the sensitive and that of the
intellective faculty. After strong stimulation of a sense we are
less able to exercise it than before, as e.g. in the case of a loud
sound we cannot hear easily immediately after, or in the case of a
bright colour or a powerful odour we cannot see or smell, but in the
case of mind thought about an object that is highly intelligible
renders it more and not less able afterwards to think objects that are
less intelligible: the reason is that while the faculty of sensation
is dependent upon the body, mind is separable from it.
Once the mind has become each set of its possible objects, as a
man of science has, when this phrase is used of one who is actually
a man of science (this happens when he is now able to exercise the
power on his own initiative), its condition is still one of
potentiality, but in a different sense from the potentiality which
preceded the acquisition of knowledge by learning or discovery: the
mind too is then able to think itself.
Since we can distinguish between a spatial magnitude and what it
is to be such, and between water and what it is to be water, and so in