Section 7
In Plato's explanation of sensation we are struck by the fact that he has not the same distinct conception of organs of sense which is familiar to ourselves. The senses are not instruments, but rather passages, through which external objects strike upon the mind. The eye is the aperture through which the stream of vision passes, the ear is the aperture through which the vibrations of sound pass. But that the complex structure of the eye or the ear is in any sense the cause of sight and hearing he seems hardly to be aware.
The process of sight is the most complicated (Rep.), and consists of three elements – the light which is supposed to reside within the eye, the light of the sun, and the light emitted from external objects. When the light of the eye meets the light of the sun, and both together meet the light issuing from an external object, this is the simple act of sight. When the particles of light which proceed from the object are exactly equal to the particles of the visual ray which meet them from within, then the body is transparent. If they are larger and contract the visual ray, a black colour is produced; if they are smaller and dilate it, a white. Other phenomena are produced by the variety and motion of light. A sudden flash of fire at once elicits light and moisture from the eye, and causes a bright colour. A more subdued light, on mingling with the moisture of the eye, produces a red colour. Out of these elements all other colours are derived. All of them are combinations of bright and red with white and black. Plato himself tells us that he does not know in what proportions they combine, and he is of opinion that such knowledge is granted to the gods only. To have seen the affinity of them to each other and their connection with light, is not a bad basis for a theory of colours. We must remember that they were not distinctly defined to his, as they are to our eyes; he saw them, not as they are divided in the prism, or artificially manufactured for the painter's use, but as they exist in nature, blended and confused with one another.
We can hardly agree with him when he tells us that smells do not admit of kinds. He seems to think that no definite qualities can attach to bodies which are in a state of transition or evaporation; he also makes the subtle observation that smells must be denser than air, though thinner than water, because when there is an obstruction to the breathing, air can penetrate, but not smell.
The affections peculiar to the tongue are of various kinds, and, like many other affections, are caused by contraction and dilation. Some of them are produced by rough, others by abstergent, others by inflammatory substances, – these act upon the testing instruments of the tongue, and produce a more or less disagreeable sensation, while other particles congenial to the tongue soften and harmonize them. The instruments of taste reach from the tongue to the heart. Plato has a lively sense of the manner in which sensation and motion are communicated from one part of the body to the other, though he confuses the affections with the organs. Hearing is a blow which passes through the ear and ends in the region of the liver, being transmitted by means of the air, the brain, and the blood to the soul. The swifter sound is acute, the sound which moves slowly is grave. A great body of sound is loud, the opposite is low. Discord is produced by the swifter and slower motions of two sounds, and is converted into harmony when the swifter motions begin to pause and are overtaken by the slower.
The general phenomena of sensation are partly internal, but the more violent are caused by conflict with external objects. Proceeding by a method of superficial observation, Plato remarks that the more sensitive parts of the human frame are those which are least covered by flesh, as is the case with the head and the elbows. Man, if his head had been covered with a thicker pulp of flesh, might have been a longer-lived animal than he is, but could not have had as quick perceptions. On the other hand, the tongue is one of the most sensitive of organs; but then this is made, not to be a covering to the bones which contain the marrow or source of life, but with an express purpose, and in a separate mass.
Section 8
We have now to consider how far in any of these speculations Plato approximated to the discoveries of modern science. The modern physical philosopher is apt to dwell exclusively on the absurdities of ancient ideas about science, on the haphazard fancies and a priori assumptions of ancient teachers, on their confusion of facts and ideas, on their inconsistency and blindness to the most obvious phenomena. He measures them not by what preceded them, but by what has followed them. He does not consider that ancient physical philosophy was not a free enquiry, but a growth, in which the mind was passive rather than active, and was incapable of resisting the impressions which flowed in upon it. He hardly allows to the notions of the ancients the merit of being the stepping-stones by which he has himself risen to a higher knowledge. He never reflects, how great a thing it was to have formed a conception, however imperfect, either of the human frame as a whole, or of the world as a whole. According to the view taken in these volumes the errors of ancient physicists were not separable from the intellectual conditions under which they lived. Their genius was their own; and they were not the rash and hasty generalizers which, since the days of Bacon, we have been apt to suppose them. The thoughts of men widened to receive experience; at first they seemed to know all things as in a dream: after a while they look at them closely and hold them in their hands. They begin to arrange them in classes and to connect causes with effects. General notions are necessary to the apprehension of particular facts, the metaphysical to the physical. Before men can observe the world, they must be able to conceive it.
To do justice to the subject, we should consider the physical philosophy of the ancients as a whole; we should remember, (1) that the nebular theory was the received belief of several of the early physicists; (2) that the development of animals out of fishes who came to land, and of man out of the animals, was held by Anaximander in the sixth century before Christ (Plut. Symp. Quaest; Plac. Phil.); (3) that even by Philolaus and the early Pythagoreans, the earth was held to be a body like the other stars revolving in space around the sun or a central fire; (4) that the beginnings of chemistry are discernible in the 'similar particles' of Anaxagoras. Also they knew or thought (5) that there was a sex in plants as well as in animals; (6) they were aware that musical notes depended on the relative length or tension of the strings from which they were emitted, and were measured by ratios of number; (7) that mathematical laws pervaded the world; and even qualitative differences were supposed to have their origin in number and figure; (8) the annihilation of matter was denied by several of them, and the seeming disappearance of it held to be a transformation only. For, although one of these discoveries might have been supposed to be a happy guess, taken together they seem to imply a great advance and almost maturity of natural knowledge.
We should also remember, when we attribute to the ancients hasty generalizations and delusions of language, that physical philosophy and metaphysical too have been guilty of similar fallacies in quite recent times. We by no means distinguish clearly between mind and body, between ideas and facts. Have not many discussions arisen about the Atomic theory in which a point has been confused with a material atom? Have not the natures of things been explained by imaginary entities, such as life or phlogiston, which exist in the mind only? Has not disease been regarded, like sin, sometimes as a negative and necessary, sometimes as a positive or malignant principle? The 'idols' of Bacon are nearly as common now as ever; they are inherent in the human mind, and when they have the most complete dominion over us, we are least able to perceive them. We recognize them in the ancients, but we fail to see them in ourselves.
Such reflections, although this is not the place in which to dwell upon them at length, lead us to take a favourable view of the speculations of the Timaeus. We should consider not how much Plato actually knew, but how far he has contributed to the general ideas of physics, or supplied the notions which, whether true or false, have stimulated the minds of later generations in the path of discovery. Some of them may seem old-fashioned, but may nevertheless have had a great influence in promoting system and assisting enquiry, while in others we hear the latest word of physical or metaphysical philosophy. There is also an intermediate class, in which Plato falls short of the truths of modern science, though he is not wholly unacquainted with them. (1) To the first class belongs the teleological theory of creation. Whether all things in the world can be explained as the result of natural laws, or whether we must not admit of tendencies and marks of design also, has been a question much disputed of late years. Even if all phenomena are the result of natural forces, we must admit that there are many things in heaven and earth which are as well expressed under the image of mind or design as under any other. At any rate, the language of Plato has been the language of natural theology down to our own time, nor can any description of the world wholly dispense with it. The notion of first and second or co-operative causes, which originally appears in the Timaeus, has likewise survived to our own day, and has been a great peace-maker between theology and science. Plato also approaches very near to our doctrine of the primary and secondary qualities of matter. (2) Another popular notion which is found in the Timaeus, is the feebleness of the human intellect – 'God knows the original qualities of things; man can only hope to attain to probability.' We speak in almost the same words of human intelligence, but not in the same manner of the uncertainty of our knowledge of nature. The reason is that the latter is assured to us by experiment, and is not contrasted with the certainty of ideal or mathematical knowledge. But the ancient philosopher never experimented: in the Timaeus Plato seems to have thought that there would be impiety in making the attempt; he, for example, who tried experiments in colours would 'forget the difference of the human and divine natures.' Their indefiniteness is probably the reason why he singles them out, as especially incapable of being tested by experiment. (Compare the saying of Anaxagoras – Sext. Pyrrh. – that since snow is made of water and water is black, snow ought to be black.)
The greatest 'divination' of the ancients was the supremacy which they assigned to mathematics in all the realms of nature; for in all of them there is a foundation of mechanics. Even physiology partakes of figure and number; and Plato is not wrong in attributing them to the human frame, but in the omission to observe how little could be explained by them. Thus we may remark in passing that the most fanciful of ancient philosophies is also the most nearly verified in fact. The fortunate guess that the world is a sum of numbers and figures has been the most fruitful of anticipations. The 'diatonic' scale of the Pythagoreans and Plato suggested to Kepler that the secret of the distances of the planets from one another was to be found in mathematical proportions. The doctrine that the heavenly bodies all move in a circle is known by us to be erroneous; but without such an error how could the human mind have comprehended the heavens? Astronomy, even in modern times, has made far greater progress by the high a priori road than could have been attained by any other. Yet, strictly speaking – and the remark applies to ancient physics generally – this high a priori road was based upon a posteriori grounds. For there were no facts of which the ancients were so well assured by experience as facts of number. Having observed that they held good in a few instances, they applied them everywhere; and in the complexity, of which they were capable, found the explanation of the equally complex phenomena of the universe. They seemed to see them in the least things as well as in the greatest; in atoms, as well as in suns and stars; in the human body as well as in external nature. And now a favourite speculation of modern chemistry is the explanation of qualitative difference by quantitative, which is at present verified to a certain extent and may hereafter be of far more universal application. What is this but the atoms of Democritus and the triangles of Plato? The ancients should not be wholly deprived of the credit of their guesses because they were unable to prove them. May they not have had, like the animals, an instinct of something more than they knew?
Besides general notions we seem to find in the Timaeus some more precise approximations to the discoveries of modern physical science. First, the doctrine of equipoise. Plato affirms, almost in so many words, that nature abhors a vacuum. Whenever a particle is displaced, the rest push and thrust one another until equality is restored. We must remember that these ideas were not derived from any definite experiment, but were the original reflections of man, fresh from the first observation of nature. The latest word of modern philosophy is continuity and development, but to Plato this is the beginning and foundation of science; there is nothing that he is so strongly persuaded of as that the world is one, and that all the various existences which are contained in it are only the transformations of the same soul of the world acting on the same matter. He would have readily admitted that out of the protoplasm all things were formed by the gradual process of creation; but he would have insisted that mind and intelligence – not meaning by this, however, a conscious mind or person – were prior to them, and could alone have created them. Into the workings of this eternal mind or intelligence he does not enter further; nor would there have been any use in attempting to investigate the things which no eye has seen nor any human language can express.
Lastly, there remain two points in which he seems to touch great discoveries of modern times – the law of gravitation, and the circulation of the blood.
(1) The law of gravitation, according to Plato, is a law, not only of the attraction of lesser bodies to larger ones, but of similar bodies to similar, having a magnetic power as well as a principle of gravitation. He observed that earth, water, and air had settled down to their places, and he imagined fire or the exterior aether to have a place beyond air. When air seemed to go upwards and fire to pierce through air – when water and earth fell downward, they were seeking their native elements. He did not remark that his own explanation did not suit all phenomena; and the simpler explanation, which assigns to bodies degrees of heaviness and lightness proportioned to the mass and distance of the bodies which attract them, never occurred to him. Yet the affinities of similar substances have some effect upon the composition of the world, and of this Plato may be thought to have had an anticipation. He may be described as confusing the attraction of gravitation with the attraction of cohesion. The influence of such affinities and the chemical action of one body upon another in long periods of time have become a recognized principle of geology.
(2) Plato is perfectly aware – and he could hardly be ignorant – that blood is a fluid in constant motion. He also knew that blood is partly a solid substance consisting of several elements, which, as he might have observed in the use of 'cupping-glasses', decompose and die, when no longer in motion. But the specific discovery that the blood flows out on one side of the heart through the arteries and returns through the veins on the other, which is commonly called the circulation of the blood, was absolutely unknown to him.
A further study of the Timaeus suggests some after-thoughts which may be conveniently brought together in this place. The topics which I propose briefly to reconsider are (a) the relation of the Timaeus to the other dialogues of Plato and to the previous philosophy; (b) the nature of God and of creation (c) the morality of the Timaeus: —
(a) The Timaeus is more imaginative and less scientific than any other of the Platonic dialogues. It is conjectural astronomy, conjectural natural philosophy, conjectural medicine. The writer himself is constantly repeating that he is speaking what is probable only. The dialogue is put into the mouth of Timaeus, a Pythagorean philosopher, and therefore here, as in the Parmenides, we are in doubt how far Plato is expressing his own sentiments. Hence the connexion with the other dialogues is comparatively slight. We may fill up the lacunae of the Timaeus by the help of the Republic or Phaedrus: we may identify the same and other with the (Greek) of the Philebus. We may find in the Laws or in the Statesman parallels with the account of creation and of the first origin of man. It would be possible to frame a scheme in which all these various elements might have a place. But such a mode of proceeding would be unsatisfactory, because we have no reason to suppose that Plato intended his scattered thoughts to be collected in a system. There is a common spirit in his writings, and there are certain general principles, such as the opposition of the sensible and intellectual, and the priority of mind, which run through all of them; but he has no definite forms of words in which he consistently expresses himself. While the determinations of human thought are in process of creation he is necessarily tentative and uncertain. And there is least of definiteness, whenever either in describing the beginning or the end of the world, he has recourse to myths. These are not the fixed modes in which spiritual truths are revealed to him, but the efforts of imagination, by which at different times and in various manners he seeks to embody his conceptions. The clouds of mythology are still resting upon him, and he has not yet pierced 'to the heaven of the fixed stars' which is beyond them. It is safer then to admit the inconsistencies of the Timaeus, or to endeavour to fill up what is wanting from our own imagination, inspired by a study of the dialogue, than to refer to other Platonic writings, – and still less should we refer to the successors of Plato, – for the elucidation of it.
More light is thrown upon the Timaeus by a comparison of the previous philosophies. For the physical science of the ancients was traditional, descending through many generations of Ionian and Pythagorean philosophers. Plato does not look out upon the heavens and describe what he sees in them, but he builds upon the foundations of others, adding something out of the 'depths of his own self-consciousness.' Socrates had already spoken of God the creator, who made all things for the best. While he ridiculed the superficial explanations of phenomena which were current in his age, he recognised the marks both of benevolence and of design in the frame of man and in the world. The apparatus of winds and waters is contemptuously rejected by him in the Phaedo, but he thinks that there is a power greater than that of any Atlas in the 'Best' (Phaedo; Arist. Met.). Plato, following his master, affirms this principle of the best, but he acknowledges that the best is limited by the conditions of matter. In the generation before Socrates, Anaxagoras had brought together 'Chaos' and 'Mind'; and these are connected by Plato in the Timaeus, but in accordance with his own mode of thinking he has interposed between them the idea or pattern according to which mind worked. The circular impulse (Greek) of the one philosopher answers to the circular movement (Greek) of the other. But unlike Anaxagoras, Plato made the sun and stars living beings and not masses of earth or metal. The Pythagoreans again had framed a world out of numbers, which they constructed into figures. Plato adopted their speculations and improved upon them by a more exact knowledge of geometry. The Atomists too made the world, if not out of geometrical figures, at least out of different forms of atoms, and these atoms resembled the triangles of Plato in being too small to be visible. But though the physiology of the Timaeus is partly borrowed from them, they are either ignored by Plato or referred to with a secret contempt and dislike. He looks with more favour on the Pythagoreans, whose intervals of number applied to the distances of the planets reappear in the Timaeus. It is probable that among the Pythagoreans living in the fourth century B.C., there were already some who, like Plato, made the earth their centre. Whether he obtained his circles of the Same and Other from any previous thinker is uncertain. The four elements are taken from Empedocles; the interstices of the Timaeus may also be compared with his (Greek). The passage of one element into another is common to Heracleitus and several of the Ionian philosophers. So much of a syncretist is Plato, though not after the manner of the Neoplatonists. For the elements which he borrows from others are fused and transformed by his own genius. On the other hand we find fewer traces in Plato of early Ionic or Eleatic speculation. He does not imagine the world of sense to be made up of opposites or to be in a perpetual flux, but to vary within certain limits which are controlled by what he calls the principle of the same. Unlike the Eleatics, who relegated the world to the sphere of not-being, he admits creation to have an existence which is real and even eternal, although dependent on the will of the creator. Instead of maintaining the doctrine that the void has a necessary place in the existence of the world, he rather affirms the modern thesis that nature abhors a vacuum, as in the Sophist he also denies the reality of not-being (Aristot. Metaph.). But though in these respects he differs from them, he is deeply penetrated by the spirit of their philosophy; he differs from them with reluctance, and gladly recognizes the 'generous depth' of Parmenides (Theaet.).
There is a similarity between the Timaeus and the fragments of Philolaus, which by some has been thought to be so great as to create a suspicion that they are derived from it. Philolaus is known to us from the Phaedo of Plato as a Pythagorean philosopher residing at Thebes in the latter half of the fifth century B.C., after the dispersion of the original Pythagorean society. He was the teacher of Simmias and Cebes, who became disciples of Socrates. We have hardly any other information about him. The story that Plato had purchased three books of his writings from a relation is not worth repeating; it is only a fanciful way in which an ancient biographer dresses up the fact that there was supposed to be a resemblance between the two writers. Similar gossiping stories are told about the sources of the Republic and the Phaedo. That there really existed in antiquity a work passing under the name of Philolaus there can be no doubt. Fragments of this work are preserved to us, chiefly in Stobaeus, a few in Boethius and other writers. They remind us of the Timaeus, as well as of the Phaedrus and Philebus. When the writer says (Stob. Eclog.) that all things are either finite (definite) or infinite (indefinite), or a union of the two, and that this antithesis and synthesis pervades all art and nature, we are reminded of the Philebus. When he calls the centre of the world (Greek), we have a parallel to the Phaedrus. His distinction between the world of order, to which the sun and moon and the stars belong, and the world of disorder, which lies in the region between the moon and the earth, approximates to Plato's sphere of the Same and of the Other. Like Plato (Tim.), he denied the above and below in space, and said that all things were the same in relation to a centre. He speaks also of the world as one and indestructible: 'for neither from within nor from without does it admit of destruction' (Tim). He mentions ten heavenly bodies, including the sun and moon, the earth and the counter-earth (Greek), and in the midst of them all he places the central fire, around which they are moving – this is hidden from the earth by the counter-earth. Of neither is there any trace in Plato, who makes the earth the centre of his system. Philolaus magnifies the virtues of particular numbers, especially of the number 10 (Stob. Eclog.), and descants upon odd and even numbers, after the manner of the later Pythagoreans. It is worthy of remark that these mystical fancies are nowhere to be found in the writings of Plato, although the importance of number as a form and also an instrument of thought is ever present to his mind. Both Philolaus and Plato agree in making the world move in certain numerical ratios according to a musical scale: though Bockh is of opinion that the two scales, of Philolaus and of the Timaeus, do not correspond…We appear not to be sufficiently acquainted with the early Pythagoreans to know how far the statements contained in these fragments corresponded with their doctrines; and we therefore cannot pronounce, either in favour of the genuineness of the fragments, with Bockh and Zeller, or, with Valentine Rose and Schaarschmidt, against them. But it is clear that they throw but little light upon the Timaeus, and that their resemblance to it has been exaggerated.
That there is a degree of confusion and indistinctness in Plato's account both of man and of the universe has been already acknowledged. We cannot tell (nor could Plato himself have told) where the figure or myth ends and the philosophical truth begins; we cannot explain (nor could Plato himself have explained to us) the relation of the ideas to appearance, of which one is the copy of the other, and yet of all things in the world they are the most opposed and unlike. This opposition is presented to us in many forms, as the antithesis of the one and many, of the finite and infinite, of the intelligible and sensible, of the unchangeable and the changing, of the indivisible and the divisible, of the fixed stars and the planets, of the creative mind and the primeval chaos. These pairs of opposites are so many aspects of the great opposition between ideas and phenomena – they easily pass into one another; and sometimes the two members of the relation differ in kind, sometimes only in degree. As in Aristotle's matter and form the connexion between them is really inseparable; for if we attempt to separate them they become devoid of content and therefore indistinguishable; there is no difference between the idea of which nothing can be predicated, and the chaos or matter which has no perceptible qualities – between Being in the abstract and Nothing. Yet we are frequently told that the one class of them is the reality and the other appearance; and one is often spoken of as the double or reflection of the other. For Plato never clearly saw that both elements had an equal place in mind and in nature; and hence, especially when we argue from isolated passages in his writings, or attempt to draw what appear to us to be the natural inferences from them, we are full of perplexity. There is a similar confusion about necessity and free-will, and about the state of the soul after death. Also he sometimes supposes that God is immanent in the world, sometimes that he is transcendent. And having no distinction of objective and subjective, he passes imperceptibly from one to the other; from intelligence to soul, from eternity to time. These contradictions may be softened or concealed by a judicious use of language, but they cannot be wholly got rid of. That an age of intellectual transition must also be one of inconsistency; that the creative is opposed to the critical or defining habit of mind or time, has been often repeated by us. But, as Plato would say, 'there is no harm in repeating twice or thrice' (Laws) what is important for the understanding of a great author.
It has not, however, been observed, that the confusion partly arises out of the elements of opposing philosophies which are preserved in him. He holds these in solution, he brings them into relation with one another, but he does not perfectly harmonize them. They are part of his own mind, and he is incapable of placing himself outside of them and criticizing them. They grow as he grows; they are a kind of composition with which his own philosophy is overlaid. In early life he fancies that he has mastered them: but he is also mastered by them; and in language (Sophist) which may be compared with the hesitating tone of the Timaeus, he confesses in his later years that they are full of obscurity to him. He attributes new meanings to the words of Parmenides and Heracleitus; but at times the old Eleatic philosophy appears to go beyond him; then the world of phenomena disappears, but the doctrine of ideas is also reduced to nothingness. All of them are nearer to one another than they themselves supposed, and nearer to him than he supposed. All of them are antagonistic to sense and have an affinity to number and measure and a presentiment of ideas. Even in Plato they still retain their contentious or controversial character, which was developed by the growth of dialectic. He is never able to reconcile the first causes of the pre-Socratic philosophers with the final causes of Socrates himself. There is no intelligible account of the relation of numbers to the universal ideas, or of universals to the idea of good. He found them all three, in the Pythagorean philosophy and in the teaching of Socrates and of the Megarians respectively; and, because they all furnished modes of explaining and arranging phenomena, he is unwilling to give up any of them, though he is unable to unite them in a consistent whole.