Infinitesimal Calculus Quotes

“Whereas Nature does not admit of more than three dimensions ... it may justly seem very improper to talk of a solid ... drawn into a fourth, fifth, sixth, or further dimension.”
― John Wallis

“The teacher manages to get along still with the cumbersome algebraic analysis, in spite of its difficulties and imperfections, and avoids the smooth infinitesimal calculus, although the eighteenth century shyness toward it had long lost all point.”
― Felix Klein, Elementary Mathematics from an Advanced Standpoint: Geometry