Beginning with the close of the eighteenth century, and continuing throughout the nineteenth, a prodigious transformation has taken place in the environment of man, which has done more to revolutionize the conditions of human life than all the changes that had taken place in the 500,000 preceding years which science has attributed to man's life on the planet. Up to the period of Watt's discovery of steam vapour as a motive power, these conditions, so far as the principal facilities of life, were substantially those of the civilization which developed eighty centuries ago on the banks of the Nile and later on the Euphrates. Man had indeed increased his conquest over Nature in later centuries by a few mechanical inventions, such as gunpowder, telescope, magnetic needle, printing-press, spinning jenny, and hand-loom, but the characteristic of all those inventions, with the exception of gunpowder, was that they still remained a subordinate auxiliary to the physical strength and mental skill of man. In other words, man still dominated the machine, and there was still full play for his physical and mental faculties. Moreover, all the inventions of preceding ages, from the first fashioning of the flint to the spinning-wheel and the hand-lever press, were all conquests of the tangible and visible forces of Nature. With Watt's utilization of steam vapour as a motive power, man suddenly passed into a new and portentous chapter of his varied history. Thenceforth, he was to multiply his powers a thousandfold by the utilization of the invisible powers of Nature--such as vapour and electricity. This prodigious change in his powers, and therefore his environment, has proceeded with ever-accelerating speed. Man has suddenly become the superman. Like the giants of the ancient fable, he has stormed the very ramparts of Divine power, or, like Prometheus, he has stolen fire of omnipotent forces from Heaven itself for his use. His voice can now reach from the Atlantic to the Pacific, and, taking wing in his aeroplane, he can fly in one swift flight from Nova Scotia to England, or he can leave Lausanne and, resting upon the icy summit of Mont Blanc--thus, like "the herald, Mercury, new-lighted on a heaven-kissing hill"--he can again plunge into the void, and thus outfly the eagles themselves. In thus acquiring from the forces of Nature almost illimitable power, he has minimized the necessity for his own physical exertion or even mental skill. The machine now not only acts for him, but too often _thinks_ for him.