gravitation from the fall of an apple; when Leverrier sought for a new planet from the perturbations of the heavenly bodies in their orbits,--we feel that deduction is as much a legitimate process as induction itself. But deductive logic is the creation of Aristotle; and it was the authority of Aristotle that Bacon sought to subvert. The inductive process is also old, of which Bacon is called the father. How are these things to be reconciled and explained? Wherein and how did Bacon adapt his method to the discovery of truth, which was his principal aim,--that method which is the great cause of modern progress in science, the way to it being indicated by him pre-eminently? The whole thing consists in this, that Bacon pointed out the right road to truth,--as a board where two roads meet or diverge indicates the one which is to be followed. He did not make a system, like Descartes or Spinoza or Newton: he showed the way to make it on sound principles. "He laid down a systematic analysis and arrangement of inductive evidence." The syllogism, the great instrument used by Aristotle and the School-men, "is, from its very nature, incompetent to prove the ultimate premises from which it proceeds; and when the truth of these remains doubtful, we can place no confidence in the conclusions drawn from them." Hence, the first step in the reform of science is to review its ultimate principles; and the first condition of a scientific method is that it shall be competent to conduct such an inquiry; and this method is applicable, not to physical science merely, but to the whole realm of knowledge. This, of course, includes poetry, art, intellectual philosophy, and theology, as well as geology and chemistry.