Gottfried Wilhelm 1646-1716 Leibnitz or Leibniz

Mathematical Writings.

At Paris Leibnitz met with Arnauld, Malebranche and Christian Huygens. This was pre eminently the period of his mathematical and physical activity. Before leaving Mainz he was able to announce (in a letter to the duke of Brunswick-Liineburg, 1671) an imposing list of dis coveries, and plans for discoveries, arrived at by means of his new logical art, in natural philosophy, mathematics, mechanics, optics, hydrostatics, pneumatics and nautical science, not to speak of new ideas in law, theology and politics. Chief among these discoveries was that of a calculating machine for performing more com plicated operations than that of Pascal—multiplying, divid ing and extracting roots, as well as adding and subtracting. This machine was exhibited to the Academy of Paris and to the Royal Society of London, and Leibnitz was elected a fellow of the latter society in April 1673. He was made a foreign member of the French academy in 1700. In Jan. 1673 he had gone to London as an attaché on a political mission from the elector of Mainz, re turning in March to Paris, and while in London had become per sonally acquainted with Oldenburg, the secretary of the Royal Society, with whom he had already corresponded, with Boyle the chemist and Pell the mathematician. It is from this period that we must date the impulse that directed him anew to mathematics. By Pell he had been referred to Mercator's Logarithmotechnica as already containing some numerical observations which Leibnitz had thought original on his own part ; and, on his return to Paris, he devoted himself to the study of higher geometry under Huy gens entering almost at once upon the series of investigations which culminated in his discovery of the differential and integral cal culus (see CALCULUS, DIFFERENTIAL AND INTEGRAL).

Shortly after his return to Paris in 1673, Leibnitz ceased to be in the Mainz service any more than in name, but in the same year entered the employment of Duke John Frederick of Bruns wick-Liineburg, with whom he had correspopded for some time.

In 1676 he removed at the duke's request to Hanover, travelling thither by way of London and Amsterdam. At Amsterdam he had many discussions with Spinoza, read his unpublished Ethica, and copied various passages from it.

For the next 4o years, and under three successive princes, Leibnitz was in the service of the Brunswick family, and his head quarters were at Hanover, where he had charge of the ducal li brary. About 1686 his thoughts and energies were partly taken up with the scheme for the reunion of the Catholic and Protestant Churches. In that year he wrote his Systema theologicum (not published until 1819), in which he strove to find common ground for Protestants and Catholics in the details of their creeds. But it was soon found that the religious difficulties were greater than had at one time appeared. A further scheme of church union in which Leibnitz was engaged, that between the Reformed and Lutheran Churches, met with no better success.

Returning from Italy in 169o, Leibnitz was appointed librarian at Wolfenbiittel by Duke Anton of Brunswick-Wolfenbiittel. Some years afterwards began his connection with Berlin through his friendship with the electress Sophie Charlotte of Brandenburg and her mother the princess Sophie of Hanover. He was invited to Berlin in 1700, and on July II of that year the academy he had planned (Akademie der Wissenschaf ten) was founded, with himself as its president for life. His genealogical researches in

Germany and Italy (1687-90)—through which he established the common origin of the families of Brunswick and Este—were not only preceded by an immense collection of historical sources, but enabled him to publish materials for a code of international law. The history of Brunswick itself was the last work of his life, and had covered the period from 768 to 1005 when death ended his la bours.

It was in the years between 1690 and 1716 that Leibnitz's chief philosophical works were composed, and during the first ten of these years the accounts of his system were, for the most part, preliminary sketches. Indeed, he never gave a full and systematic account of his doctrines. His views have to be gathered from let ters to friends, from occasional articles in the Acta Eruditorum, the Journal des Savants, and other journals, and from one or two more extensive works. In 1710 appeared the only complete philo sophical work of his life-time, Essais de Theodicee sur la bonte de Dieu, la liberte de l'homme, et l'origine du mal, originally undertaken at the request of the late queen of Prussia, who had desired a reply to Bayle's opposition of faith and reason. In he wrote, for Prince Eugene of Savoy, a sketch of his system under the title of La Monadologie, and in the same year appeared his Principes de la nature et de la grace. The last few years of his life were perhaps more occupied with correspondence than any others, and, in a philosophical regard, were chiefly notable for the letters, which, through the desire of the new queen of England, he interchanged with Clarke, sur Dieu, l' l'espace, la duree.

Leibnitz died on Nov. 14, 1716, his closing years enfeebled by disease, harassed by controversy, embittered by neglect ; but to the last he preserved the indomitable energy and power of work to which is largely due the position he holds as a man of almost universal attainments and almost universal genius. Neither at Berlin, in the academy which he had founded, nor in London, whither his sovereign had gone to rule, was any notice taken of his death. At Hanover, Eckhart, his secretary, was his only mourner; "he was buried," says an eyewitness, "more like a rob ber than what he really was, the ornament of his country" (Mem oirs of John Ker of Kersland, by himself, 1726, i. 118). Only in the French academy was the loss recognized, and a worthy eulogium devoted to his memory (Nov. 13, 1717). The tooth an niversary of his birth was celebrated in 1846, and in the same year were opened the Koniglichsdchsische Gesellschaft der Wissen schaften and the Kaiserliche Akademie der Wissenschaften in Leipzig and Vienna respectively. In 1883 a statue was erected to him at Leipzig.

Leibnitz possessed a wonderful power of rapid and continuous work. Even when travelling his time was employed in solving mathematical problems. He is described as moderate in his habits, quick of temper but easily appeased, charitable in his judgments of others, and tolerant of differences of opinion, though impa tient of contradiction on small matters. He is also said to have been fond of money to the point of covetousness; he was cer tainly desirous of honour, and felt keenly the neglect in which his last years were passed.