Mersenne, Marin (1588–1648), French mathematician, scientist, and theologian. Mersenne was born in the hamlet of La Soultière in the parish of Oizé, the son of Julien Mersenne, a farmer of modest means, and his wife, Jeanne Moulière. When a new Jesuit school at La Flèche opened in 1604, strongly supported by King Henry IV, Mersenne immediately transferred there, graduating in 1608. He continued his studies at the Sorbonne for two years, leaving to join the Order of Minims, a mendicant order founded in the fifteenth century by St. Francis of Paola, and in 1614 was sent to teach at their convent in Nevers.
There he began writing letters to ask the advice of others, primarily about scientific matters. In 1619 he moved to the Minim convent in Paris and continued writing to an ever-expanding group of scientists. As a result, he knew or corresponded with most of the leading scientists of his day. He often sent them a list of questions and then communicated their replies to others to encourage further work on the responses he received. His correspondence, published in the twentieth century, contains a wealth of information about many of the scientific ideas of the period. The letters Mersenne exchanged with René Descartes, for example, are an important source for studying the development of Descartes's ideas.
In 1635 Mersenne further encouraged the exchange of ideas by establishing a group called the Academia Parisiensis, which met on Thursdays and was attended by the outstanding scientists and mathematicians of his day. It was continued by others after his death and was an important forerunner of the Académie des Sciences.
Mersenne published over twenty books during his lifetime, and a treatise on optics appeared after his death. He began with the stated objective of examining the latest ideas in natural philosophy to see what their impact on Catholic theology might be and to show that, if properly understood, they did not threaten religion. As he continued to write and publish, he put more emphasis on science itself, but never forgot his purpose in studying it.
His first work, Quaestiones Celeberrimae in Genesim (1623; Well-known questions on Genesis), was written as a commentary on the book of Genesis in which he interspersed the text with an examination of a number of current ideas troubling religion. He dealt with atheism by providing thirty-five "proofs" of the existence of God. He also defended religious miracles against an attack by the Renaissance naturalist Julius Caesar Vanini, who had been executed as an atheist in Toulouse in 1619, by underscoring the limitations of scientific explanations. In the third part of the work, given the separate title Observationes, he pointed out flaws in Hermetic and magical accounts of natural phenomena. In the middle section, he addressed scientific questions such as whether the earth moves, or whether the heavenly spheres are solid, and gave a description of magnetism, drawing on the De Magnete (On the magnet) of the English physician William Gilbert (1544–1603).
His next work, L'impiété des déistes . . . (1624; The impiety of deists), developed some of these criticisms further. He then turned to a consideration of the nature of scientific theories in La vérité des sciences . . . (1625; The truth of the sciences), concluding that we cannot know their truth and that we must settle for "mitigated skepticism" or a science of probabilities.
In the 1630s Mersenne published several works in which he advocated treating nature quantitatively and analyzing it mathematically. In these works he reported on the latest developments in science. He also demonstrated his admiration for the work of Galileo by publishing in 1634 a French paraphrase of an early manuscript of Galileo's on mechanics. In Questions théologiques, physiques, morales et mathématiques (Theological, physical, moral, and mathematical questions), he summarized Galileo's arguments for the motion of the earth from The Two Chief World Systems, the work that resulted in Galileo's condemnation by the Inquisition, although he was careful to remove the arguments from a copy he gave a friend to carry to Rome. He did include the Inquisition's sentence against Galileo. He also published a French version of Galileo's Two New Sciences, his major contribution to physics.
One of the sciences that interested Mersenne was music. Medieval scholars had considered it a form of mathematics, and Mersenne accepted that designation. He discussed music in several of his publications, but especially in his Harmonie universelle . . . (1635–1636), in which he described the musical instruments of his day and how they were played, analyzing musical theory and harmony, and developing his own musical philosophy.
In the 1640s he concentrated more directly on the physical sciences, such as ballistics, hydraulics, pneumatics, mechanics, and the recent work on air pressure.
Satisfied that he had helped to remove obstacles to further research, Mersenne believed that science was progressing along a path that would not clash with religion.
Bibliography
Primary Source
Mersenne, Marin. Correspondance du P. Marin Mersenne. 17 vols. Paris, 1932–1988.
Secondary Sources
Beaulieu, Armand. Mersenne: le grand minime. Brussels, 1995. By the last editor of Mersenne's correspondance.
Dear, Peter. Mersenne and the Learning of the Schools. Ithaca, N.Y., 1988. A careful evaluation of Mersenne's philosophy of science.
Lenoble, Robert. Mersenne ou la naissance du mécanisme. Paris, 1943. The standard work on Mersenne.
—WILLIAM L. HINE
