by one individual, but the new advance, the higher flight, the closing victory, fell to the lot of the same extraordinary person. [Note 3\1: _Hist. Inductive Sciences_, b. v. c. iv. sect. 3.] The attraction of the sun upon the planets, of the moon upon the earth, of the planets on each other, of the parts of the earth on themselves, of the sun and {52} moon upon the ocean;--all these truths, each of itself a great discovery, were included by Newton in the higher _generalization_, of the universal gravitation of matter, by which each particle is drawn to every other according to the law of the inverse square: and thus this long advance from discovery to discovery, from truths to truths, each justly admired when new, and then rightly used as old, was closed in a worthy and consistent manner, by a truth which is the most worthy admiration, because it includes all the researches of preceding ages of Astronomy. We may take another example of a succession of this kind from the history of a science, which, though it has made wonderful advances, has not yet reached its goal, as physical astronomy appears to have done, but seems to have before it a long prospect of future progress. I now refer to Chemistry, in which I shall try to point out how the preceding discoveries afforded the materials of the succeeding; although this subordination and connexion is, in this case, less familiar to men's minds than in Astronomy, and is, perhaps, more difficult to present in a clear and definite shape. Sylvius saw, in the facts which occur, when an acid and an alkali are brought together, the evidence that they neutralize each other. But cases of neutralization, and acidification, and many other effects of mixture of the ingredients of bodies, being thus viewed as _facts_, had an aspect of unity and law given them by Geoffroy and Bergman[4\1], who introduced the _conception_ of the Chemical Affinity or Elective Attraction, by which certain elements select other elements, as if by preference. That combustion, whether a chemical union or a chemical separation of ingredients, is of the same nature with acidification, was the doctrine of Beccher and Stahl, and was soon established as a truth which must form a part of every succeeding physical theory. That the rules of affinity and chemical composition may include gaseous elements, was established by Black and Cavendish. And all these truths, thus brought to light by {53} chemical discoverers,--affinity, the identity of acidification and combustion, the importance of gaseous elements,--along with all the facts respecting the weight of ingredients and compounds which the balance disclosed,--were taken up, connected, and included as _particulars_ in the oxygen _theory_ of Lavoisier. Again, the results of this theory, and the quantity of the several ingredients which entered into each compound--(such results, for the most part, being now no longer mere theoretical speculations, but recognized