Christiaan Huygens (14 April 1629 – 8 July 1695) was a Dutch mathematician, astronomer, physicist, probabilist and horologist. His 1673 scientific masterpiece was Horologium Oscillatorium, a treatise on the mathematical theory and applications of the isochronous pendulum clock, which led to improved accuracy in the measurement of time. He is also noted for his opposition to the Newtonian corpuscular theory of light, providing a longitudinal wave theory which hypothesized propagation by spherical waves emitted along a wave front.

Christiaan Huygens — Letter to Pierre Perrault, 'Sur la préface de M. Perrault de son traité de l'Origine des fontaines' (1673), Oeuvres Complètes de Christiaan Huygens (1897), Vol. 7, 298. Quoted in Jacques Roger, The Life Sciences in Eighteenth-Century French Thought, ed. Keith R. Benson and trans. Robert Ellrich (1997), 163

Christiaan Huygens — (1692) writing five years after the appearance of Newton's Principia, as quoted in A. R. Manwell, Mathematics Before Newton (Oxford University Press, 1959), p. 56 – «He [Huygens] said, indeed, that the idea of universal attraction [gravitation] 'appears to me absurd'.»

Christiaan Huygens — Horologium Oscillatorium (1673) as quoted by Joella G. Yoder, "Christiaan Huygens, Book on the Pendulum Clock" in Landmark Writings in Western Mathematics 1640-1940 ed., Ivor Grattan-Guinness (2005).