TWO:Engines operated by means of hot air, called caloric engines, and engines operated by gas, or explosive substances, all act substantially upon the same general principles as steam-engines; the greatest distinction being between those engines wherein the generation of heat is by the combustion of fuel, and those wherein heat and expansion are produced by chemical action. With the exception of a limited number of caloric or air engines, steam machinery comprises nearly all expansive engines that are employed at this day for motive-power; and it may be safely assumed that a person who has mastered the general principles of steam-engines will find no trouble in analysing and understanding any machinery acting from expansion due to heat, whether air, gas, or explosive agents be employed.Here, then, we find, chiefly among the rustic population, a religion intimately associated with morality, and including the doctrine of retribution after death. But this simple faith, though well adapted to the few wants of its original votaries, could not be raised to the utmost expansion and purity of which it was susceptible without being brought into vivifying contact with that other Olympian religion which, as we have seen, belonged more peculiarly to the ruling aristocracy. The poor may be more moral than the rich, and the country than the town; nevertheless it is from dwellers in cities, and from the higher classes, including as they do a large percentage of educated, open-minded individuals, that the impulses to moral progress always proceed. If the narrowness and hardness of primitive social arrangements were overcome; if justice was disengaged from the ties of blood-relationship, and tempered with consideration for inevitable error; if deadly feuds were terminated by a habitual appeal to arbitration; if the worship of one supreme ideal was substituted for a blind sympathy with the ebb and flow of life on earth; if the numerical strength of states was increased by giving shelter to fugitives; if a Hellenic nation was created and held together by a common literature and a common civilisation, by oracles accessible to all, and by periodical games in which every free-born Greek could take part; and, lastly, if a brighter abode than the slumberous garden of Persephon was assigned after death to the godlike heroes who had come forth from a thrice repeated ordeal with souls unstained by sin;55all this was due to the military rather than to the industrial classes, to the spirit that breathes through Homer69 rather than to the tamer inspiration of Hesiods muse. But if justice was raised to an Olympian throne; if righteous providence, no less than creative power, became an inalienable attribute of Zeus; if lyric poetry, from Archilochus to Simonides and Pindar, is one long hymn of prayer and praise ever turned upward in adoring love to the Divine; we must remember that Themis was a synonyme for Earth, and that Prometheus, the original friend of humanity, for whose benefit he invented every useful art, augury included, was her son. The seeds of immortal hope were first planted in the fructifying bosom of Dmtr, and life, a forsaken Ariadn, took refuge in the mystical embraces of Dionysus from the memory of a promise that had allured her to betray. Thus, we may conjecture that between hall and farm-house, between the Olympian and the Chthonian religions, there was a constant reaction going on, during which ethical ideas were continually expanding, and extricating themselves from the superstitious elements associated with their earliest theological expression.
