Opticks: or, A treatise of the reflections, refractions, inflections and colours of light

About this book

Isaac Newton’s Opticks is a scientific treatise that gathers the results of his experiments on light, colour, reflection and refraction. The work opens with a candid preface in which Newton explains that portions of the discourse were presented to the Royal Society in 1675, later expanded, and only now published at the urging of friends. He stresses that earlier papers were incomplete, and that the present volume contains only what he considers sufficiently proven, deliberately avoiding speculation. The first book then proceeds to lay out a series of definitions and axioms, rays, refrangibility, angles of incidence and reflection, followed by detailed geometric constructions for predicting the paths of light through prisms, lenses and mirrors. Newton’s methodical style, anchored in experimental observation and mathematical reasoning, sets the tone for the entire work.

The voice is that of an early‑18th‑century natural philosopher, formal and meticulous, interweaving Latin‑flavoured terminology with plain English explanations. Its dense, definition‑driven prose and extensive diagrammatic instructions will appeal to readers who relish the historical development of physics, scholars of the scientific revolution, and anyone interested in the foundations of optics before the modern era of wave theory.

Opening lines

Part of the ensuing Discourse about Light was written at the Desire of some Gentlemen of the Royal-Society, _in the Year 1675, and then sent to their Secretary, and read at their Meetings, and the rest was added about twelve Years after to complete the Theory; except the third Book, and the last Proposition of the Second, which were since put together out of scatter'd Papers. To avoid being engaged in Disputes about these Matters, I have hitherto delayed the printing, and should still have delayed it, had not the Importunity of Friends prevailed upon me. If any other Papers writ on this Subject are got out of my Hands they are imperfect, and were perhaps written before I had tried all the Experiments here set down, and fully satisfied my self about the Laws of Refractions and Composition of Colours. …

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