Epicurus assumed the existence of matter, force and motion,—Stoff und Kraft. He held that all space was filled with molecules of matter in a state of rapid motion in every direction. These molecules were subject to gravity and endowed with properties or forces. One combination of molecules gave rise to unorganized matter, another to life, another to mind; and from the various combinations, guided by unintelligent physical laws, all the wonderful organisms of plants and animals have arisen. To these combinations also all the phenomena of life, instinct, and intelligence in the world are to be referred. This theory has been adopted in our day by a large class of scientific men, especially in Germany. The modern advocates of the theory are immeasurably superior to the ancient Epicureans in their knowledge of astronomy, botany, zoÖlogy, and biology; but in their theory of the universe, and in their mode of accounting for all the phenomena of life and intelligence, they are precisely on the same level. They have not added an idea to the system, which has ever been regarded as the opprobrium of human thought. BÜchner, Moleschott, Vogt, hold that matter is eternal and indestructible; that matter and force are inseparable: the one cannot exist without the other. What, it is asked, is motion without something moving? What is electricity without an electrified body? What is attraction without molecules attracting each other? What is contractibility without muscular fibre, or secretion without a secreting gland? One combination of molecules exhibits the phenomena of life, another combination exhibits the phenomena of mind. All this was taught by the old heathen philosopher more than two thousand years ago. That this system denies the existence of God, of mind as a thinking substance distinct from matter, and of the possibility of the conscious existence of man after death, are not inferences drawn by opponents, but conclusions openly avowed by its advocates.