Abstract
On the occasion of the tercentenary of the death of Christiaan Huygens, his contributions to optics, more particularly to the wave theory of light, are critically reviewed against the background of the work of Kepler, Descartes and Newton. Recent historiography has shown that Huygens' work was overshadowed by Newton's and Euler's during the 18th century. In the beginning of the 19th century however, 'Huygens' principle' and its foremost application, the analysis of double refraction, were rediscovered by Thomas Young and Augustin Fresnel. Huygens' principle indeed appeared to be easily adaptable to the new theory of transversal light waves. Up to the present day, Fresnel's transversal interpretation of Huygens' principle has been a precious aid in understanding the foundations of optics.