Marin, an eminent philosopher and mathematician, of the religious order of the Minimes, was born at Oyse in France in 1588, and studied at the college of La Flèche, where he made the friendship of Descartes, then a student at the same institution,—an intimacy which was kept up during their lives. He afterwards studied at the university of Paris and at the Sorbonne; and in 1613 he became a priest of the order of the Minimes. In his new sphere he commenced the study of the Hebrew language, and very soon mastered it. He held the philosophical chair of Nevers during the three years preceding 1619, when he became superior of the convent of his order in the neighbourhood of Paris. He afterwards travelled in Germany and Italy, and became acquainted during his visit to the latter country with the recent discoveries of Torricelli respecting a vacuum. Mersenne ultimately settled at Paris, where he died in 1648, lamented by a large circle of distinguished friends, who admired alike the gentle engaging manners of the man and the profound sagacity of the philosopher.

Some have ascribed to Mersenne the first discovery of the cycloid; an honour, however, to which he does not seem to be entitled. Some of the wits of his time affected to hold him in low esteem, and he was even charged with plagiarism by the Abbé Le Vayer, who calls him "Le bon Larron"; but it is a sufficient vindication of the Father's talents and character that the celebrated Descartes not only clung fast to him as a friend, but, as his correspondence amply testifies, consulted him on the most important points of his speculations. Mersenne's most famous work is the Harmonie Universelle, contenant la Theorie et la Pratique de la Musique, 2 vols., Paris, 1636-7. This work he afterwards translated into Latin, with important alterations and additions, rendering it almost an entirely new treatise, and entitled Harmonicorum libri xii, de Sonorum Natura, Causis et Effectibus, Paris, 1648, fol.