the structure of the universe. It was ready for publication in
1633, but news of GALILEO GALILEI’s arrest was enough to
keep Descartes from printing the book, and it remained
unpublished until 14 years after his death. His major
contributions to mathematics came in his next work, which
included three books entitled La Dioptrique, Les Météores,
and La Géométriein which he is credited for inventing
analytical geometry. He is responsible for the use of symbols
to represent quantities; symbols for EXPONENTs; moving the
TERMs of an EQUATIONto one side of the equation; showing
how to find indeterminate COEFFICIENTs to solve equations;
and defining the elements for a point on a PLANE, using two
fixed lines drawn at RIGHT ANGLEs on a plane, each of which
represent negative and positive VALUEs, to determine the
coordinates xand yof a point for an equation of a curve (he
dealt only with curves), which are elements of the Cartesian
GRAPH. Descartes claimed that he dreamt of analytical
geometry one night in November 1619, and this was when he
decided to pursue his ideas. He was known as having a cold
disposition, and made it a personal mission to discredit
PIERRE DE FERMAT. Descartes, who had been very sick as a
young child, once told BLAISE PASCALthat the secret to
maintaining his health was to sleep until 11:00 A.M. and to
never let anyone make him get up before that hour. In 1650
Descartes moved to Stockholm, and met with the queen, at
her request, every morning at 5:00. The walk to the palace in
the cold air took its toll, and he died a few months later of
pneumonia.Diophantus of Alexandria(ca. 200–84) The Greek mathematician
often called the “father of algebra,” who was the first to use
symbols, or VARIABLEs, to represent unknown quantities. He
wrote a 13-volume work entitled Arithmetica,which dealt with
algebraic EQUATIONs and number theory, and contained 130
problems and their SOLUTIONs for determinate equations, as
well as indeterminate equations, which are also known as
Diophantine equations.Dirichlet, Johann Peter Gustav Lejeune (1805–59) Belgian
mathematician who at the age of 20 was the first to prove n= 5
when the number divisible by 5 is even, for Fermat’s LastBIOGRAPHIES Diophantus of Alexandria – Dirichlet
BIOGRAPHIES Diophantus of Alexandria – Dirichlet
René Descartes (Engraving
by W. Holl, from the original
picture byFrancis Hals in the
gallery of the Louvre, Cour-
tesy of AIP Emilio Segrè
Visual Archives)