Some discussion about priority of invention led Dr. Keill to maintain Newton’s title to be considered the sole inventor of the fluxional calculus. Leibnitz had asserted that he had been in possession of the method eight years before he communicated it to Newton. He appealed to the Royal Society, of which Newton was President, and that body gave judgment on the question in 1712. Their decision is now worth nothing; firstly, because it only determined that Newton was the _first_ inventor, which was not the whole point, and left out the question whether Leibnitz had or had not stolen from Newton; secondly, because the charge of plagiarism is insinuated in the assertion that a copy of Newton’s letter, as above mentioned, had been sent to Leibnitz. Now they neither prove that he had received this letter in time sufficient to enable him to communicate with Newton as above described, or, if he had received it, that there was in it a sufficient hint of the method of fluxions. The decision of posterity is, that Leibnitz fairly invented his own method; and though English writers give no strong opinion as to the fairness with which the dispute was carried on, we imagine that there are few who would now defend the conduct of their predecessors. Whoever may have had priority of invention, it is clear that to Leibnitz and the Bernoullis belongs the principal part of the superstructure, by aid of which their immediate successors were enabled to extend the theory of Newton; and thus Leibnitz is placed in the highest rank of mathematical inventors. The metaphysics of Leibnitz have now become a by-word. He is pre-eminent, among modern philosophers, for his extraordinary fancies. His monads, his pre-established harmony, and his best of all possible worlds, are hardly caricatured in the well-known philosophical novel of Voltaire. If any thinking monad should find that the pre-established harmony between his soul and body would make the former desire to see more of Leibnitz as a metaphysician, and the latter able to second him, we can inform him that it was necessary, for the best of all possible universes, that Michael Hansch should in 1728 publish the whole system at Frankfort and Leipzic, under the title, ‘Leibnitzii Principia philosophica more geometrico demonstrata;’ and also that M. Tenneman should give an account of this system, and M. Victor Cousin translate the same. It is not easy to give any short description of the contents, nor would it be useful. A school of metaphysicians of the sect of Leibnitz continued to exist for some time in Germany, but it has long been extinct.