Opticks by the English physicist and mathematician Sir Isaac Newton (1642-1727), published in 1704 with a colour spectrum produced by a prism projected across the title page. This work was based on Newton's own experimental investigations into the behaviour of light. In Opticks he discussed topics such as the refraction of light by prisms and the rings of coloured light formed between a lens and a mirror in contact with each other (later termed Newton's rings). In Isaac Newton's time, it was believed that white light was colourless, and that the prism itself produced the colour. Newton's experiments convinced him that all the colours already existed in the light in a heterogeneous fashion, and that \corpuscles\" (particles) of light were fanned out because particles with different colours travelled with different speeds through the prism."