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the heart, all he says is that it takes place in the heart, or, at the most, he holds that the principle and source of our perceptions is the region round the heart. And however confusedly Aristotle states his view, he would seem to hold, not that the heart itself compares and distinguishes our different sensations: but simply that it is through the heart that the process is effected: that it is in short the condition and concomitant, not the cause of our perceptions.
The question therefore of the relation of the heart to the perceptive act resolves itself into the more general question of the relation between mind and body as conceived by Aristotle. But, as we have already seen, body as such is, from Aristotle's point of view, simply dead and useless matter, and it is only through the co-operation of the mind that it attains to its full meaning. Perception is in fact, to repeat a passage which we have already noticed, an affection of the mind through the body: it involves the combination of at once physiological and psychological conditions for its exercise. The mind can therefore be affected only through the material organs which form its substratum: while the body only attains to the faculty of real perception through the immanent action of the mind. And thus if that consciousness and comparison of sensations which is required to combine and distinguish different sensations can take place only through the assistance of the blood-producing, centrally located heart: it must be remembered, on the other hand, that it is only through that mind or soul which is the truth of body that the heart can go beyond the physical processes for which it is adapted.
It was not improbably in a simple spirit of antagonism to Plato that Aristotle referred the common categories which enter into our perceptions to the sensitive faculty itself. Plato had distinguished in the clearest terms between the particular object of the separate senses and the general conceptions which entered into all of them. The perceptions of one power, he remarks in the Theaetetus (p. 185), cannot be perceived by an
other faculty-what is perceived by hearing cannot be perceived by sight, the object of sight cannot be perceived by hearing. Further, he goes on, each of these senses is identical with itself and different from any other. But these common qualities of sameness and difference cannot be perceived by either of the senses in question themselves: they are as little competent to judge of this as they (in place of taste) can decide whether two objects are bitter or not. The same result holds good of all general categories-being and not-being, likeness and unlikeness, sameness and difference, unity and number. There is no special organ (idiov opravov), Plato holds, by which they are to be perceived, but the mind by its own action apprehends the general ideas which enter into every object. And similarly in the Republic, Plato shews how number arises out of the inability of sense to distinguish between its different reports-how the mind, finding that the senses report to it about one thing as now hard now soft, is obliged to consider whether each of its reports are one or two. (Bk. VII, 524).
The opposition which is here apparent between the Platonic and the Aristotelian Psychology is probably one of the many instances in which the difference between the two thinkers is little else than one of terminology. It seems no doubt as if Aristotle, in ascribing the categories which enter into every object of experience to sense itself, or even central sense, was necessarily in direct antithesis to Plato, who refers them to what he calls the 'mind.' But this central sense of Aristotle means evidently much the same as Plato's 'mind.' As the power which contributes a consciousness of sensation and enables us to distinguish and compare sensations, it is clearly not a sensitive but an intellectual operation. And a writer less enslaved than Aristotle was to terminology would have left the problem to be explained by reference to the indivisible action of the mind as the synthetic factor in our existence. The doctrine of a central or common sense remains an instance of the fictitious entities which an analytic psychology pushed to extremes tends to create.
X. IMAGINATION, DREAMS AND MEMORY.
Sense-perception, we have seen, is viewed by Aristotle as a sort of movement excited in the substance of the corporeal organ of sensation by the medium which intervenes between the organ and the quality which constitutes the object of sensation. Now this movement or impression does not always vanish with the disappearance of the object which has caused it'. There are of course many cases in which a stronger sensation overpowers and buries a weaker, just as a bright fire puts out a feebler or a greater sorrow overshades a smaller. The struggle for existence among our sensations, the mutual play in which our different impressions cross and cover one another, is recognised by Aristotle in a manner which the followers of Herbart have been particularly ready to recognise. Amid this crossing and recrossing of sensations there are some which make their way upward to the surface and leave a trace or relic (uový) of themselves. The sensitive impression in short stamps itself as it were upon the sense and its effect continues after the object of sensation is withdrawn. There may of course be different degrees in this persistence of sensations. The impression may be such that it requires a conscious effort to revive it: or it may be so vividly printed that we cannot for a time get rid of it. Thus, Aristotle remarks, we see nothing if we suddenly transfer ourselves from sunlight to a darkened room, because the movement which the light excited still persists within the eyes: or if again we close our eyes after gazing long at a brilliant light we are presented with a succession of pictures of different colours which ultimately close with black. This is an extreme instance of the manner
1 De Insomn. 1, 46ο, ἀπελθόντος τοῦ θύραθεν αἰσθητοῦ ἐμμένει τὰ αἰσθήματα αἰσθητὰ ὄντα.
* De Sensu, c. 1, 447 15, ἀεὶ ἡ μείζων κίνησις τὴν ἐλάττω ἐκκρούει. De Insomn. 3, 461*1.
3 De Insomn. 2, 4599, μεταφερόντων τὴν αἴσθησιν ἀκολουθεῖ τὸ πάθος, οἷον ἐκ τοῦ
in which a sensitive impression persists and leaves its trace behind it: and it is upon this fact that imagination (pavracía) as conceived by Aristotle depends.
Imagination is accordingly defined by Aristotle as "the movement which results upon an actual sensation':" more simply we may describe it as the after-effect of a sensation, the continued presence of an impression after the object which first excited it has been withdrawn from actual experience. Hobbes indeed was little else than translating Aristotle when he wrote: "All fancies are motions within us, reliques of those made in the sense." The pictures of imagination in fact are simply a result of the general law of nature that the movement of one substance prolongs itself and gets communicated to another. And hence it is that in the Rhetoric, Imagination is described as weak sensation or, in the language of Hobbes, "decaying sense'."
Further light is thrown by Aristotle on this conception of Imagination by contrasting it with several other of the mental operations with which it is not to be identified. Imagination, the Psychology itself explains, must not be regarded as either sensation, opinion, thought or scientific knowledge. With sensation it is of course intimately associated. The faculty for receiving sensations is in fact fundamentally identical with that which forms pictures of imagination: but they manifest themselves in different ways: they are different aspects of a faculty which may be looked at now in this way now in that. At the same time there remains a decided difference between sensation
ἡλίου εἰς τὸ σκότος· συμβαίνει γὰρ μηδὲν ὁρᾶν διὰ τὴν ἔτι ὑποῦσαν κίνησιν ἐν τοῖς ὄμμασιν ὑπὸ τοῦ φῶτος κ.τ.λ.
1 De An. III. 3, 4391, ἡ φαντασία ἂν εἴη κίνησις ὑπὸ τῆς αἰσθήσεως τῆς KAT' évépyeιav yiyvoμévn. Cp. 45917. 'Imagination' means much more than pavracía, but seems the nearest English equivalent. Vorstellung corresponds much more closely to Aristotle's conception.
2 Freudenthal has collected a number of passages in which Hobbes' expressions strikingly recall Aristotle.
3 De An. III. 3, 428b10.
4 Rhetor. 1. 11, 137018, ἡ φαντασία ἐστὶν αἴσθησίς τις ἀσθενής.
5 De Insomn. 1. 45915, ἔστι μὲν τὸ αὐτὸ τῷ αἰσθητικῷ τὸ φανταστικόν, τὸ δ' εἶναι φανταστικῷ καὶ αἰσθητικῷ ἕτερον.
and imagination. Sense requires an object to excite it into action, while imagination may arise without the help of any outward object: sense is always ready to act when needed, imagination is much more capricious: sensation is the property of every animal, imagination is a more exclusive faculty (the bee would seem to have it, the worm would seem to be without it): the reports of sense are as such always true, whereas the pictures of imagination are often the reverse: and lastly sense and imagination often stand in inverse ratio to one another-we have an image when our senses are remiss-nay, images frequently present themselves to us when our eyes are closed'.
Opinion or doğa is however the mental phenomenon from which Aristotle thinks it especially important to distinguish Imagination. Even if opinion be not like scientific knowledge | always true, but like imagination liable to error, there is one property connected with opinion which marks it definitely off from imagination. For opinion is attended with belief (IOTIS): it implies a readiness to act upon the view it entertains and while imagination seems a characteristic of many animals, belief of this sort would seem to attach to none. Belief again implies an act of thought or reason: and such reason is no attribute of animal existence. Nor, Aristotle continues, will it mend the matter, to regard imagination as a combination of opinion and sensation. Upon this supposition, the opinion under consideration must be of the same object as the sensation: that is, it is not the combination of the idea of good and the sensation of white which will constitute imagination: the sensation and the idea must alike refer to the same quality or object. The result then of this theory must be to identify imagination with the direct immediate conception of a sensation. But conception, argues Aristotle, does not in this way correspond with the presentations of our image-forming faculty. The 'image' which we form of the sun is that of a surface one foot in diameter: our
De An. III. 3, 428'1—18.
2 41551, τὸ οὖν φαίνεσθαί ἐστι τὸ δοξάζειν ὅπερ αἰσθάνεται μὴ κατὰ συμβεβηκός.