ONE:
FORE:In working to regular scales, such as one-half, one-eighth, or one-sixteenth size, a good plan is to use a common rule, instead of a graduated scale. There is nothing more convenient for a mechanical draughtsman than to be able to readily resolve dimensions into various scales, and the use of a common rule for fractional scales trains the mind, so that computations come naturally, and after a time almost without effort. A plain T square, with a parallel blade fastened on the side of the head, [80] but not imbedded into it, is the best; in this way set squares can pass over the head of a T square in working at the edges of the drawing. It is strange that a draughting square should ever have been made in any other manner than this, and still more strange, that people will use squares that do not allow the set squares to pass over the heads and come near to the edge of the board.
FORE: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.167It is probable that the philanthropic tendencies of the Stoics were, to a great extent, neutralised by the extreme individualism which formed the reverse side of their philosophical character; and also by what may be called the subjective idealism of their ethics. According to their principles, no one can really do good to any one else, since what does not depend on my will is not a good to me. The altruistic virtues are valuable, not as sources of beneficent action, but as manifestations of benevolent sentiment. Thus, to set on foot comprehensive schemes for the relief of human suffering seemed no part of the Stoics business. And the abolition of slavery, even had it been practicable, would have seemed rather superfluous to one who held that true freedom is a mental condition within the reach of all who desire it,88 while the richest and most powerful may be, and for the most part actually are, without it. Moreover, at the time when41 philosophy gained its greatest ascendency, the one paramount object of practical statesmen must have been to save civilisation from the barbarians, a work to which Marcus Aurelius devoted his life. Hence we learn without surprise that the legislative efforts of the imperial Stoic were directed to the strengthening, rather than to the renovation, of ancient institutions.89 Certain enactments were, indeed, framed for the protection of those who took part in the public games. It was provided, with a humanity from which even our own age might learn something, that performers on the high rope should be ensured against the consequences of an accidental fall by having the ground beneath them covered with feather beds; and the gladiators were only allowed to fight with blunted weapons.90 It must, however, be noted that in speaking of the combats with wild beasts which were still allowed to continue under his reign, Marcus Aurelius dwells only on the monotonous character which made them exceedingly wearisome to a cultivated mind; just as a philosophic sportsman may sometimes be heard to observe that shooting one grouse is very like shooting another; while elsewhere he refers with simple contempt to the poor wretches who, when already half-devoured by the wild beasts, begged to be spared for another days amusement.91 Whether he knew the whole extent of the judicial atrocities practised on his Christian subjects may well be doubted; but it maybe equally doubted whether, had he known it, he would have interfered to save them. Pain and death were no evils; but it was an evil that the law should be defied.92
