Isaac Newton argued that the geometric nature of reflection and refraction of light could only be explained if light were made of particles, referred to as corpuscles because waves do not tend to travel in straight lines. Newton sought to disprove Christiaan Huygens' theory that light was made of waves. In his 44th trial in a series of experiments concerning the physics of light, he concluded that light is made of particles and not waves by having passed a beam of white light through two prisms which were held at such an angle that the light split into a spectrum after passing through the first prism and then was recomposed, back into white light, by the second prism.