But how did these atoms come together? Here Democritus showed a prophetic clearness of sight which may well astonish modern critics. He regarded motion in these atoms as a primal fact, probably deriving it from the theory of Heracleitus. He held that as these atoms collided in the void, not always directly, but obliquely, the striking and the struck assumed a rotatory motion, and so established vortices which either attracted suitable atoms or rejected others by the centrifugal force of this rotation. Thus were constructed not only the great spheres that we observe in the sky, but all the ordinary objects around us. Into his explanations of the causes of the irregular forms of these objects I cannot enter, by reason of their intricacy. But to what consequences his theory led him may be told you in a sentence. He maintained, with the imagination of a great scientific mind, that there were an endless number of world-systems through space, differing merely in magnitude, some furnished with several moons, some in process of becoming, others, owing to collisions, in process of destruction, some of them wholly deficient in moisture, and hence devoid of animal and plant life. These are all consequences which we have drawn from the use of the telescope and even the spectroscope, but which this wonderful man reached by way of philosophical thinking. Aristotle makes it his chief objection to the Atomic theory that it is purely descriptive of phenomena without assigning any cause for the primeval motion of the atoms; that it recognises no Architect, no Demiurge who set the myriad crowd of particles into motion, and then into regulated action. But Aristotle was misled by an assumption which has infected philosophy down to the present day--the assumption that a state of rest is prior to, and more natural to matter than a state of motion. This prejudice did not mislead Democritus, though it is an idol not only of the cave, as Bacon would say, but also of the forum. We have been misled and deceived by relative want of motion, to consider that until disturbed by an active impulse matter occupies a fixed place. But now, I would almost say since the twentieth century dawned, this old fallacy is giving way to the newer conception that there is no such thing as rest in nature, nay not even within the particles of any solid body. So then the primal assumption of the Greek thinker that motion is the natural state of matter was a wonderful anticipation of science, and shows once more what giant strides the human race may make by thinking as compared with the mere recording of experiments. Even now, when students of experimental physics are degenerating into mere mechanics, who seek to interrogate nature by the use of delicate machinery, and carefully recorded occurrences, I am assured by those in our great University who have been compelled in earlier life to acquire a sound knowledge of Greek philosophy, that the study of the old