Page images
PDF
EPUB

tinctly gained the upper hand. On the Atomic theory we explain to-day the laws of sound, of light, of heat, of chemical and physical changes in things in the widest sense, and yet Atomism is as little able to-day as in the time of Demokritos to explain even the simplest sensation of sound, light, heat, taste, and so on. In all the advances of science, in all the modifications of the notion of atoms, this chasm has remained unnarrowed, and it will be none the less when we are able to lay down a complete theory of the functions of the brain, and to show clearly the mechanical motions, with their origin and their results, which correspond to sensation, or, in other words, which effect sensation. Science must not despair, by the means of this powerful weapon, of success in deriving even the most complicated processes and most significant motives of a living man, according to the laws of the persistence of force, from the impulses that are set free in his brain under the influence of the nervous stimuli; but she is for ever precluded from finding a bridge between what the simplest sound is as the sensation of a subject— mine, for instance-and the processes of disintegration in the brain which science must assume in order to explain this particular sensation of sound as a fact in the objective world.

In the manner in which Demokritos cut this Gordian knot we may perhaps trace the influence of the Eleatic School. They explained motion and change in general as mere phenomena, and, in fact, non-existent phenomena. Demokritos limited this destructive criticism to sense qualities. "Only in opinion consists sweetness, bitterness, warmth, cold, colour; in truth, there is nothing but the atoms and empty space." 20

Since to him, therefore, the Immediately Given-sensation-had something deceptive about it, it is easily intelligible that he complained that the truth lies deep hidden,

2 Mullach, 357 : “ νόμῳ γλυκὺ καὶ νόμῳ πικρὸν, νόμῳ θερμόν, νόμῳ ψυχ

ρόν, νόμῳ χροιή· ἐτεῇ δὲ ἄτομα καὶ κενόν.”

and that he attributed more weight to reflection with regard to knowledge than to immediate perception. His reflection dealt with notions that kept close to the perceptions of sense, and were for that very reason suited to explain nature. From the one-sidedness of those whose hypotheses are mere deductions from notions Demokritos was saved by this, that he constantly tested his theory of the atomic movements by picturing it to himself in the forms of sense.

IV. The atoms are infinite in number, and of endless variety of form. In the eternal fall through infinite space, the greater, which fall more quickly, strike against the lesser, and lateral movements and vortices that thus arise are the commencement of the formation of worlds. Innumerable worlds are formed and perish successively and simultaneously.21

The magnitude of this conception has often in antiquity

21 The main features of Atomism we must, in defect of authentic fragments, take in the main from Aristotle and Lucretius; and we may remark, that even in these accounts, far removed as they are from the ridiculous disfigurements and misunderstandings of a Cicero, yet the mathematical clearness of the premisses and the connection of the individual parts has probably suffered. We are, therefore, justified in completing the defective tradition, though always in the sense of that mathematico-physical theory on which Demokritos's whole system hangs. So the procedure of Zeller, e.g., is undoubtedly quite right when treating the relation of size and weight of the atoms (i. 698702); on the other hand, there is even here, in the doctrine of motion, still a remnant left of the want of clearness so persistent in all later accounts. Zeller observes (p. 714), that the idea that in infinite space there is no above and below, appears not to have forced itself upon the Atomists; that what

Epikuros, in Diogenes, x. 60, says on this point is too superficial and unscientific to be credited to Demokritos. But this judgment is too decided; for Epikuros by no means opposes, as Zeller (iii. i. 377, &c.) supposes, to the objection of there being no above and below in infinite space ocular evidence only; but he makes the quite correct, and therefore, it may be, quite Demokritean remark, that in spite of this relativity of "above" and “below" in infinite space, yet that the direction from head to foot is a definitely given notion, and that from foot to head may be regarded as the opposed notion, however much we may suppose the line on which these dimensions are measured to be prolonged. In this direction follow the general movement of the free atoms, and clearly only in the sense of the movement from the head to the foot of a man standing in the line, and this direction is that from above to below

the directly opposite one that from below nowards.

been considered as something quite monstrous, and yet it stands much nearer to our modern ideas than that of Aristotle, who proved a priori that besides his self-contained world there could be no second. When we come to Epikuros and Lucretius, where we have fuller information, weshall discuss more thoroughly their cosmical theory. Here we will only mention that we have every reason to suppose that many features of the Epikurean Atomism, in cases where we are not told the contrary, are due to Demokritos. Epikuros made the atoms infinite in number, but not infinitely various in form. More important is his innovation in reference to the origin of the lateral motion.

Here Demokritos gives us a thoroughly logical view, although one which cannot be maintained in face of our modern physics; but yet it shows that the Greek thinker carried out his speculations as far as was then possible in subjection to strictly physical principles. Starting from the erroneous view that greater bodies-the same density being assumed-fall quicker than smaller ones, he made greater atoms in their descent overtake and strike the smaller. But as the atoms are of various shapes, and the collision will not take place in the centre of the atoms, then, even according to the principles of modern mechanical science, revolutions of the atoms on their axes and lateral motions will be set up. When once set up, these lateral motions must ever become more and more complicated, and as the collision of constant new atoms with a layer of atoms already in lateral motion constantly imparts new forces, so we may suppose that the motion will continually increase.

From the lateral motions in connection with the rotation of the atoms are then easily produced cases of retrogressive movement. If now, in a layer of atoms so involved, the heavieri.e., the larger-atoms continually receive a stronger impetus downwards, they will finally be collected below, while the light ones will form the upper stratum. The basis of this whole theory, the doctrine of the quicker

descent of the greater atoms,22 was attacked by Aristotle, and it appears that Epikuros was thus induced, whilst retaining the rest of the system, to introduce his fortuitous deviations of the atoms from the straight line. Aristotle, that is, taught that if there could be void space, which he thought impossible, then all bodies must necessarily fall with equal speed, since the difference in the rapidity of the descent is determined by the various densities of the medium-as, for example, water and air. Now void space not being a medium, there is no difference therefore in the descent of different bodies. Aristotle in this case was at one with our modern science, as also in his doctrine of gravitation towards the centre of the universe. His deduction, however, is only in places rational, and is mixed with subtleties of the same kind as those by which he seeks to demonstrate the impossibility of motion in empty space. Epikuros cut the matter short, and comes to this simple conclusion: because in empty space there is no resistance, all bodies must fall equally fast-apparently in entire agreement with modern physics; but only apparently, since the true theory of gravitation of descent was wholly wanting to the ancients.

22 Comp. Fragm. Phys., 2, Mullach, p. 358, and the admirable remark of Zeller, i. 717, Anm. 1, on the purely mechanical nature of this aggregation of the homogeneous atoms. But it is less certain whether the vortical movement (the "Kreis- oder Wirbelbewegung," Zeller, p. 715, and Anm. 2) really played the part in Demokritos's system attributed to it by later reporters. It seems much more likely that he made the vortical movement of the mass of atoms of which the world was composed only develop itself after the atoms, and especially those of the outer covering of the universe, had formed a compact body held together by the hooks of the atoms. Such a body might then very easily, partly by the original motion of its particles, partly by the

impact of the atoms rushing in from without attain a rotatory motion. The stars, according to Demokritos, are moved by the rotating covering of the world. Epikuros, of course, who was, however, it is certain, a very weak mathematician as compared with Demokritos, in spite of his being later, thought it also possible that the sun may maintain its continual revolution round the earth in consequence of the impulse once received in the general movement of the universe; and if we consider how vague were the pre-Galilean ideas as to the nature of motion, we need not be surprised that even Demokritos should have made a vortical motion be developed out of the rectilinear impact; but convincing proofs of this view are entirely wanting.

It is not uninteresting to compare how Galilei, as soon as, after many painful efforts, he had reached the true law of fall, directly ventured a priori to the conclusion that in empty space all bodies will fall equally fast, a considerable period before this, by means of the air-pump, could be proved to be the fact. It is a question to be considered. how far reminiscences of Aristotle or Lucretius may not have assisted Galilei to this conclusion.23

V. The variety of all things is a consequence of the variety of their atoms in number, size, figure, and arrangement; there is no qualitative difference of atoms. They have no "internal conditions;" and act on each other only by pressure or collision.24

We have already seen, in connection with the third proposition, that Demokritos regarded the sense qualities, such as colour, sound, heat, and so on, as mere deceptive appearances, which is only to say that he entirely sacrificed the subjective side of phenomena, which is, nevertheless, all that is immediately given, in order to be able to carry out a more consequent objective explanation; and accordingly Demokritos engaged, in fact, in the most exhaustive investigations as to what must be, in the object, the substratum of the sensible qualities.

According, then, to the difference in the arranging of the atoms in a "schema"-which may remind us of the schemata" or atoms of our chemists-are determined our subjective impressions.25

Aristotle complains that Demokritos had reduced all

23 Comp. Whewell, Hist. of the Induct. Sci., ii. 34 (ed. 1837).

24 Here again the authentic proofs are lacking; we have chiefly to rely upon reports of Aristotle, which are herc, however, very full, and raise no suspicion of misunderstanding. Fuller details in Zeller, i. 704 ff.

25 Here we have tolerably full extracts in Theophrastos; comp. Fragm. Phys., 24-39, Mullach, p. 362 sqq.

Noteworthy is the general principle
in Fr. 24: "The schemia is in itsel)
[κα0 avró], the sweetness, however,
and the sensible quality is only in
relation to another and in another."
Here we have, too, the source of the
Aristotelian opposition of substance
and accident, just as Aristotle found
the original of his apposition of
dúvauis and èvépyeta in Demokritos.
(Fragm. Phys., 7, Mullach, p. 358).

« PreviousContinue »