Search Loci: Convergence:
[The universe] cannot be read until we have learnt the language and become familiar with the characters in which it is written. It is written in mathematical language, and the letters are triangles, circles and other geometrical figures, without which means it is humanly impossible to comprehend a single word.
Opere Il Saggiatore, p. 171.
This is the title page of the 1779 edition of the works of Isaac Newton (1642-1727) known at that time. Note that this work, edited by Samuel Horsley, is a much shorter book than the recent eight volume collection of Newton's mathematical papers, edited by Derek Whiteside.
This is the beginning of Newton's first letter to Leibniz (the Epistola prior), sent through Henry Oldenburg on June 13, 1676. This letter (from vol. 1, p. 285) contains some of Newton's work on the calculus, including his first statement of the binomial theorem.
This page (vol. 2, p. 359) is from Newton's Principia Mathematica. It is the discussion of Proposition 29, Problem 6 from Book 2, Section 6 of that work.
This diagram, Table IV from volume 4, shows how refraction of light is the cause of the rainbow.
This page, from vol. 3, p. 420, illustrates refraction of light through triangular prisms.