Enraptured over heat. Jean-Baptiste-Joseph Fourier was born on March 21, 1768, at Auxerre, France, the son of a tailor. He was orphaned at eight, cared for by a charitable lady, and sent to the local military school run by the Benedictine Order. At the age of twelve he wrote stirring sermons for some of the leading church dignitaries of Paris, and thought of becoming a priest. Instead he became a teacher of mathematics, first at his local school and then later at the Ecole Normale and the Ecole Polytechnique. In 1798 he enthusiastically joined Gaspard Monge in Napoleon's ill-fated Egyptian campaign.
Of his scholarly achievements, Fourier is today best known for his celebrated The'orie analytique de la chaleur (Analytical Theory of Heat) of 1822, which proved to be a landmark in mathematical physics. This work was an extension of ideas that ten years earlier won him the Academic prize for an essay on the mathematical theory of heat, and it was in this work that Fourier contributed the idea that almost any function y = f (x) can be represented by a trigonometric (or, as it is called today, a Fourier) series. Lord Kelvin described the work as "a great mathematical poem."
Fourier's experience in Egypt, and maybe his work on heat, later induced within him a curious habit. He became convinced that desert heat is the ideal condition for good health. He accordingly clothed himself in many layers of garments and lived in rooms of unbearably high temperature. Some believe that this obsession with heat may have hastened his death, the more immediate cause of which was heart disease. He died, thoroughly cooked, on May 16, 1830, in his sixty-third year.
Perhaps Fourier's most quoted sentence (it appeared in his early work on the mathematical theory of heat) is: " The deep study of nature is the most fruitful source of mathematical discoveries."