Opticks (1704) is Newton's work on the nature of light. Through prism experiments he demonstrated that white light is composed of all the colors of the spectrum and formulated the corpuscular theory of light — the idea that light consists of particles. The work is an accessible experimental treatise, written in English rather than the Latin of the Principia, which set the agenda for optical physics throughout the 18th century. His enormous authority conditioned the initial rejection of the wave theory and turned refuting Newton into the implicit challenge for Young and Fresnel.