In optics, the corpuscular theory of light, set forward by Sir Isaac Newton, says that light is made up of small discrete particles called "corpuscles" (little particles) which travel in straight line with a finite velocity and possess kinetic energy.This theory also rules out the presence of any medium for propagation of light. In its contemporary incarnation, the theory of photons, this idea explains many properties of light, in particular the photoelectric effect. However, it fails to explain other effects, such as interference and diffraction. It was therefore superseded by the wave theory of light, later understood as part of electromagnetism, and eventually supplanted by modern quantum mechanics and the wave–particle duality.
Newton's theory remained in force for more than 100 years and took precedence over Huygens' wave front theory, partly because of Newton’s great prestige. However when the corpuscular theory failed to adequately explain the diffraction, interference and polarization of light it was abandoned in favour of Huygen's wave theory.
Newton's corpuscular theory was an elaboration of his view of reality as interactions of material points through forces. Note Albert Einstein's description of Newton's conception of physical reality:
[Newton's] physical reality is characterised by concepts of space, time, the material point and force (interaction between material points). Physical events are to be thought of as movements according to law of material points in space. The material point is the only representative of reality in so far as it is subject to change. The concept of the material point is obviously due to observable bodies; one conceived of the material point on the analogy of movable bodies by omitting characteristics of extension, form, spatial locality, and all their 'inner' qualities, retaining only inertia, translation, and the additional concept of force.