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Rh into a mathematical criticism of the opinion of Plato "that the motion of the planets is such as if they had all been created by God in some region very remote from our system, and let fall from thence towards the sun, their falling motion being turned aside into a transverse one whenever they arrived at their several orbits." This, of course, is wholly unlike Herschel's theory, or that of Laplace. But of these letters Sir David says: "In the present day they possess a peculiar interest. They show that the Nebular Hypothesis, the dull and dangerous heresy of the age, is incompatible with the established laws of the material universe, and that an omnipotent arm was required to give the planets their position and motions in space, and a presiding intelligence to assign to them the different functions they had to perform."

These views of Sir David Brewster, eminent man of science though he was and sincere believer in an almighty arm ruling all the motions of material bodies, do not seem justified by facts. Even his great name is not weighty enough to counterbalance that of Laplace, when the former affirms and the latter denies that the Nebular Hypothesis "is incompatible with the established laws of the material universe." Newton's speculations on Plato's dream of the origin of planets had nothing to do with the hypothesis in question. It may be "a dull and dangerous heresy," as Sir David believed, "but it denies neither an almighty arm nor a presiding mind." Recent discoveries have given more probability to the theory—if we are entitled to use that name: and Herschel's inductions from observed and classified facts have gone far to prove that Laplace's