Considered one of the great works of science in history, Opticks: or, A Treatise of the Reflexions, Refractions, Inflexions and Colours of Light is a book by English natural philosopher Isaac Newton that was published in English in 1704. The book analyzes the fundamental nature of light by means of the refraction of light with prisms and lenses, the diffraction of light by closely spaced sheets of glass, and the behaviour of color mixtures with spectral lights or pigment powders. The publication of Opticks represented a major contribution to science, different from but in some ways rivalling the Principia. Opticks is largely a record of experiments and the deductions made from them, covering a wide range of topics in what was later to be known as physical optics. That is, this work is not a geometric discussion of catoptrics or dioptrics, the traditional subjects of reflection of light by mirrors of different shapes and the exploration of how light is "bent" as it passes from one medium, such as air, into another, such as water or glass. Rather, the Opticks is a study of the nature of light and colour and the various phenomena of diffraction, which Newton called the "inflexion" of light. ***** Einstein’s Forward to Opticks, 1931 Fortunate Newton, happy childhood of science! He who has time and tranquility can by reading this book live again the wonderful events which the great Newton experienced in his young days. Nature to him was an open book, whose letters he could read without effort. The conceptions which he used to reduce the material of existence to order seemed to flow spontaneously from experience itself, from the beautiful experiments which he ranged in order like playthings and describes with an affectionate wealth of detail. On one person he combined the experimenter, the theorist, the mechanic and, not least, the artist in exposition. —Albert Einstein