Nicole d'Oresme, sometimes referred to as Nicole Oresme or Nicholas of Oresme, pioneered the use of fractional exponents, and developed a type of coordinate geometry centuries before René Descartes (1596-1650). He discussed the Earth's rotation as well, and further distinguished himself with his writings on economics and his service to France's King Charles V.
Born in Normandy, Nicole studied theology and later enrolled in the College of Navarre at the University of Paris. He served as master of the college from 1356-1361, and in 1370 became royal chaplain in the court of Charles V. Much of his most important mathematical work dates from the 1360s.
In one book, published in about 1360, Nicole made the first use of fractional exponents, or fractional powers. (The notation in use today for expressing this idea, however, had not yet been developed.) Elsewhere he discussed a logical relationship between the calculating and graphing of values, thus paving the way for his own rudimentary form of coordinate geometry. In particular, Nicole suggested that a graph could be plotted for a variable magnitude whose value was a function—to use the terminology employed by modern mathematicians—of another. Descartes may indeed have been influenced by Oresme's work, which was later printed and saw numerous reprints.
Questiones super libros Aristotelis de anima, a commentary on Aristotle (384-322 b.c.) written in about 1370, discussed the Greek philosopher's ideas about the motion of the earth—ideas which by the time of the Renaissance would be proven wrong. To a degree Nicole anticipated these later critiques, maintaining initially that the earth is not stationary, and that a daily rotation would be possible. In the end, however, he went back on his own position, and embraced that of Aristotle. The Questiones also examined the nature of light, particularly its speed and reflective qualities.
Charles commissioned Nicole to prepare translations, from Latin to French, of several other works by Aristotle, an important step in the spread of knowledge from the scholars-only world of Latin to the vernacular tongues of Europe. Nicole also wrote an attack on astrology, Du divinacions (On divination), in which he maintained that events with alleged astrological causes can be explained by scientific phenomena instead. Perhaps his most famous work of any kind was De moneta (On money), written between 1355 and 1360, in which he maintained that a ruler has an obligation not to debase (reduce the precious-metal content) the currency of his people.
In 1377, Nicole was appointed bishop of Lisieux. He died in that town five years later, on July 11, 1382.