It is unnecessary to recommend this treatise to readers. Is it necessary to praise the work, the author of which is the great Newton. We first present here the public lectures that Newton began to give in Cambridge when in 1669 Barrow handed him the professorship of the Lukasov department. They contain discoveries about light and colors made by the author in 1666 and reported in 1671 to the Royal Society and published in the same year in Philosophical Transactions