ADMIRERS of the great men of literature and philosophy are often surprised to find that the scientific activity of their heroes, to which biographers give so much weight, passes unnoticed by modern scientists. Rabelais's renown in medicine, Descartes's work in physics and optics--and, dare one add, Valéry's mathematics--are more highly prized by their literary followers than by the specialists concerned in these particular fields. This is not the case with Pascal; while Torricelli rightly takes precedence over him in his work on the vacuum, Pascal's own experiments, and his presentation of their results, are still acknowledged as models of scientific method; Fermat, whom he modestly addressed as the greatest geometer in Europe, is today put on the same level by mathematicians as Pascal, whose work on probability and conic sections is still classic; the omnibus service inaugurated by Pascal testifies even more strikingly to his practical gifts, though few of the millions who use it know to whom they owe the debt. While remaining well on this side idolatry, one may reasonably disagree with all Pascal himself claimed to stand for and continue to admire him as a person of extraordinary gifts. Though there is less support than formerly for the view that Pascal came to his last religious phase as a sort of fanatical renegade from science and mathematics, there is no doubt that it was in these fields that certain thought patterns and methods had become firmly established in his mind before he began to apply them to religious problems. It may be helpful to study these separately before going on to the Pensées.
Two characteristic ideas are already to be found in most of his work, whether mathematical, scientific, or psychological, before they reach their fullest development in the Pensées, and even if Pascal may not be their inventor, he is their clearest exponent. In their many different forms these ideas may be summed up as the theory of orders and the theory of intellectual approach. In the Traité du vide, Entretien avec M. De Saci, De l'Esprit géométrique,