Various Works

  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