Jean d'Alembert

lived from 1717 to 1783

D'Alembert was a pioneer in the study of differential equations and pioneered their use of in physics. He studied the equilibrium and motion of fluids.

Find out more at: http://www-history.mcs.st-andrews.ac.uk/history/Mathematicians/D'Alembert.html

Some quotes:
 

Thus metaphysics and mathematics are, among all the sciences that
belong to reason, those in which imagination has the greatest role. I
beg pardon of those delicate spirits who are detractors of mathematics for saying this .... The imagination in a mathematician who creates makes no less difference than in a poet who invents.... Of all the great men of antiquity, Archimedes may be the one who most deserves to be placed beside Homer.
Discours Preliminaire de L'Encyclopedie, Tome 1, 1967. pp 47 - 48.
 
Algebra is generous: she often gives more than is asked for.
Quoted in D MacHale, Comic Sections (Dublin 1993)
 
Allez en avant, et la foi vous viendra.
(push on and faith will catch up with you.)  [advice to those who questioned the calculus] Quoted in A L Mackay, Dictionary of Scientific Quotations (London 1994)
 
One magnitude is said to be the limit of another magnitude when the
second may approach the first within any given magnitude, however
small, though the second may never exceed the magnitude it approaches.
The article on Limite in the Encyclopdie ,1754.
 
Geometry, which should only obey Physics, when united with it sometimes commands it. If it happens that the question which we wish to examine is too complicated for all the elements to be able to enter into the analytical comparison we wish to make, we separate the more inconvenient [elements], we substitute others for them, less
troublesome but also less real, and we are surprised to arrive,
notwithstanding a painful labour, only at a result contradicted by
nature; as if after having disguised it, cut it short or altered it, a
purely mechanical combination could give it back to us.
Essai d'une nouvelle thorie de la rsistance des fluides (1752).