THREE:Returning to Epicurus, we have next to consider how he obtained the various motions required to bring his atoms into those infinite combinations of which our world is only the most recent. The conception of matter naturally endowed with capacities for moving in all directions indifferently was unknown to ancient physics, as was also that of mutual attraction and85 repulsion. Democritus supposed that the atoms all gravitated downward through infinite space, but with different velocities, so that the lighter were perpetually overtaken and driven upwards by the heavier, the result of these collisions and pressures being a vortex whence the world as we see it has proceeded.163 While the atomism of Democritus was, as a theory of matter, the greatest contribution ever made to physical science by pure speculation, as a theory of motion it was open to at least three insuperable objections. Passing over the difficulty of a perpetual movement through space in one direction only, there remained the self-contradictory assumption that an infinite number of atoms all moving together in that one direction could find any unoccupied space to fall into.164 Secondly, astronomical discoveries, establishing as they did the sphericity of the earth, had for ever disproved the crude theory that unsupported bodies fall downward in parallel straight lines. Even granting that the astronomers, in the absence of complete empirical verification, could not prove their whole contention, they could at any rate prove enough of it to destroy the notion of parallel descent; for the varying elevation of the pole-star demonstrated the curvature of the earths surface so far as it was accessible to observation, thus showing that, within the limits of experience, gravitation acted along convergent lines. Finally, Aristotle had pointed out that the observed differences in the velocity of falling bodies were due to the atmospheric resistance, and that, consequently, they would all move at the same rate in such an absolute vacuum as atomism assumed.165 Of these objections Epicurus ignored the first two, except, apparently, to the extent of refusing to believe in the antipodes. The third he acknowledged, and set himself to evade it by a hypothesis striking at the root of all scientific86 reasoning. The atoms, he tells us, suffer a slight deflection from the line of perpendicular descent, sufficient to bring them into collision with one another; and from this collision proceeds the variety of movement necessary to throw them into all sorts of accidental combinations. Our own free will, says Lucretius, furnishes an example of such a deflection whenever we swerve aside from the direction in which an original impulse is carrying us.166 That the irregularity thus introduced into Nature interfered with the law of universal causation was an additional recommendation of it in the eyes of Epicurus, who, as we have already mentioned, hated the physical necessity of the philosophers even more than he hated the watchful interfering providence of the theologians. But, apparently, neither he nor his disciples saw that in discarding the invariable sequence of phenomena, they annulled, to the same extent, the possibility of human foresight and adaptation of means to ends. There was no reason why the deflection, having once occurred, should not be repeated infinitely often, each time producing effects of incalculable extent. And a further inconsequence of the system is that it afterwards accounts for human choice by a mechanism which has nothing to do with free-will.167Euripides is not a true thinker, and for that very reason fitly typifies a period when religion had been shaken to its very foundation, but still retained a strong hold on mens minds, and might at any time reassert its ancient authority with unexpected vigour. We gather, also, from his writings, that ethical sentiment had undergone a parallel transformation. He introduces characters and actions which the elder dramatists would have rejected as unworthy of tragedy, and not only introduces them, but composes elaborate speeches in their defence. Side by side with examples of devoted heroism we find such observations as that everyone loves himself best, and that those are most prosperous who attend most exclusively to their own interests. It so happens that in one instance where Euripides has chosen a subject already handled by Aeschylus, the difference of treatment shows how great a moral revolution had occurred in the interim. The conflict waged between Eteocls and Polyneics for their fathers throne is the theme both of the Seven against Thebes and of the Phoenician Women. In both, Polyneics bases his claim on grounds of right. It had been agreed that he and his brother should alternately hold sway over Thebes. His turn has arrived, and Eteocls refuses to give way. Polyneics endeavours to enforce his pretensions by bringing a foreign army against Thebes. Aeschylus makes him appear before the walls with an allegorical figure of Justice on his shield, promising to restore him to his fathers seat. On hearing this, Eteocls exclaims:
FORE:"My dear sir, they are in my possession. If you are still cynical on the point I will show them to you."
THREE:"Rather. An expert couldn't do it under an hour. Both those tyres will have to come off. Now what are we to do?""Not at all! If you step outside, you can see them standing, ten minutes from here. Near Lixhe they threw a bridge across the Meuse. It is the third already which they put down, for each time they are smashed from the fort. Oh, it is horrible; there must surely fall a number of dead, and here we have seen corpses in the Meuse already.... But I do not understand how you ventured to come here...."
FORE:It has been the fashion in certain quarters to look down on these early thinkersto depreciate the value of their speculations because they were thinkers, because, as we have already noticed, they reached their most important conclusions by thinking, the means of truly scientific observation not being within their reach. Nevertheless, they performed services to humanity comparable for value with the legislation of Solon and Cleisthenes, or the victories of Marathon and Salamis; while their creative imagination was not inferior to that of the great lyric and dramatic poets, the great architects and sculptors, whose contemporaries they were. They first taught men to distinguish between the realities of nature and the illusions of sense; they discovered or divined the indestructibility of matter and its atomic constitution; they taught that space is infinite, a conception so far from being self-evident that it transcended the capacity of Aristotle to grasp; they held that the seemingly eternal universe was brought into its present form by the operation of mechanical forces which will also effect its dissolution; confronted by the seeming permanence and solidity of our planet, with the innumerable varieties of life to be found on its surface, they declared that all things had arisen by differentiation8 from a homogeneous attenuated vapour; while one of them went so far as to surmise that man is descended from an aquatic animal. But higher still than these fragmentary glimpses and anticipations of a theory which still awaits confirmation from experience, we must place their central doctrine, that the universe is a cosmos, an ordered whole governed by number and law, not a blind conflict of semi-conscious agents, or a theatre for the arbitrary interference of partial, jealous,6 and vindictive gods; that its changes are determined, if at all, by an immanent unchanging reason; and that those celestial luminaries which had drawn to themselves in every age the unquestioning worship of all mankind were, in truth, nothing more than fiery masses of inanimate matter. Thus, even if the early Greek thinkers were not scientific, they first made science possible by substituting for a theory of the universe which is its direct negation, one that methodised observation has increasingly tended to confirm. The garland of poetic praise woven by Lucretius for his adored master should have been dedicated to them, and to them alone. His noble enthusiasm was really inspired by their lessons, not by the wearisome trifling of a moralist who knew little and cared less about those studies in which the whole soul of his Roman disciple was absorbed.
THREE:The principle upon which steam-engines operate may be briefly explained as follows:
FORE:But there was nothing to be gained by going back. With the diamonds stuffed in his pocket, Balmayne returned to the dining-room. Maitrank sat on the sofa with his head between his hands moaning to himself. He had slipped off his heavy sable-lined overcoat, for the atmosphere of the room was oppressive.Another matter to be considered is that the engineering apprentice, in estimating what he will have to learn, must not lose sight of the fact that what qualifies an engineer of to-day will fall far short of the standard that another generation will fix, and of that period in which his practice will fall. This I mention because it will have much to do with the conceptions that a [9] learner will form of what he sees around him. To anticipate improvement and change is not only the highest power to which a mechanical engineer can hope to attain, but is the key to his success.
