THREE:There is a problem as to the principle of action in a Barker wheel, which although it may be very clear in a scientific sense, remains a puzzle to the minds of many who are well versed in mechanics, some contending that the power is directly from pressure, others that it is from the dynamic effect due to reaction. It is one of the problems so difficult to determine by ordinary standards, that it serves as a matter of endless debate between those who hold different views; and considering the advantage usually derived from such controversies, perhaps the best manner of disposing of the problem here is to state the two sides as clearly as possible, and leave the reader to determine for himself which he thinks right.Our philosopher appears to more advantage as a critic than as a religious dogmatist. He meets the Stoic belief in Providence by pointing out the undeniable prevalence of evils which omnipotent benevolence could not be supposed to tolerate; the Stoic optimism, with its doctrine, still a popular one, that all things were created for the good of man, by a reference to the glaring defects which, on that hypothesis, would vitiate the arrangements of Nature; the Stoic appeal to omens and prophecies by showing the purely accidental character of their fulfilment.160 But he trusts most of all to a radically different explanation of the world, an explanation82 which everywhere substitutes mechanical causation for design. Only one among the older systemsthe atomism of Democritushad consistently carried out such a conception of Nature, and this, accordingly, Epicurus adopts in its main outlines.
