Mersennus (Fr, Mersenne), Marin
Mersennus (Fr., Mersenne), Marin a. very learned French ecclesiastic and philosopher, was born in 1588 at Oyse, in the present department of Maine. He received his education at the College of La Fleche, where he was a fellow-student of Des Cartes, and with him he formed an intimacy, which a similarity of pursuits ripened into a friendship dissolved only by death. He also studied at the University of Paris, and subsequently at the Sorbonne. In 1612 he took the vows at the Minimes, in the neighborhood of Paris. In the year following entering the priesthood, :he deemed it incumbent on him to study the Hebrew language, and addressed himself to the accomplishment of this task. In 1615 he filled the chair of philosophy at Nevers, and there taught till the year 1619, when he was chosen superior of the convent, and, on completing the term of his office, he travelled in Germany, Italy, and the Netherlands. He finally settled in Paris, where his gentle temper and polite and engaging manners procured him a number of distinguished friends. Of these the chief was the founder of the Cartesian philosophy, who entertained the highest opinion of his abilities, and consulted him upon all occasions. It has been stated - though the story seems highly improbable that Des Cartes, by the advice of Mersenne, at once changed his intention of founding his system on the principle of a vacuum, and adopted that of a plenum. The discovery of the cycloid has been ascribed to him and also to Des Cartes, but it now seems pretty clear that to neither are we indebted for the first notice of this curve. Mersenne died at Paris in 1648. Pere Mersenne was undoubtedly a man of great learning and unwearied research, and deserved the esteem. in which he was held by the philosophers and literati of his age; but, except his Harmonie Universelle, his works are now unread and almost unknown. If by some he was overrated, by others he has been undervalued; and when Voltaire mentioned him as "Le minime et tres minime Pere Mersenne," he' indulged his wit at the expense of one with whose writings, it is to be suspected, he was very little acquainted. His eulogist, however, in the Dictionnaire Historique, admits that Mersennus very ingeniously converted the thoughts of others to his own use; and the abbe Le Vayer calls him "Le bon Larron" a skilful pilferer. Nevertheless, the work above named, L'Harmonie Universelle, contenant la Theorie et la Pratique de'la Musique (1637,2 vols. fol.), has proved of the utmost value to all later writers on the subject. The work was, in 1648, translated into Latin and enlarged by the author; but both the original and translation have now become as rare as they are curious. Another, but earlier production of his, La Verite des Sciences contre les Sceptiques (Paris, 1625), discusses at considerable length the nature of mathematical evidence, and concludes by maintaining that mental philosophy, jurisprudence, and all the arts and sciences, should be taught and illustrated through the aid of mathematics (liv. i, ch. 8, 10, 13, 14). "The mind itself," he held, "is the real and effective source of all its powers and perceptions of abstract truth" (p.
193). See Hilarion de Coste, Vie du R. P. Marin de Mersenne; Niceron, Hommes illustres, vol. 32; Blakey, Hist. of the Philosophy of Mind, 2:423 sq. (J. H W.)