Kepler's discovery would not have been possible without the doctrine of conics. Now contemporaries of Kepler-such penetrating minds as Descartes and Pascal-were abandoning the study of geometry ... because they said it was so UTTERLY USELESS. There was the future of the human race almost trembling in the balance; for had not the geometry of conic sections already been worked out in large measure, and had their opinion that only sciences apparently useful ought to be pursued, the nineteenth century would have had none of those characters which distinguish it from the ancien régime.
Charles Sanders PeirceBad reasoning as well as good reasoning is possible; and this fact is the foundation of the practical side of logic.
Charles Sanders PeirceThis branch of mathematics [Probability] is the only one, I believe, in which good writers frequently get results which are entirely erroneous.
Charles Sanders Peirce