### „For the things of this world cannot be made known without a knowledge of mathematics.“

— Roger Bacon, book Opus Majus

Cited in: Opus majus: A translation by Robert Belle Burke. Vol 1 (1962). p. 128

Opus Majus, c. 1267

Context: For the things of this world cannot be made known without a knowledge of mathematics. For this is an assured fact in regard to celestial things, since two important sciences of mathematics treat of them, namely theoretical astrology and practical astrology. The first … gives us definite information as to the number of the heavens and of the stars, whose size can be comprehended by means of instruments, and the shapes of all and their magnitudes and distances from the earth, and the thicknesses and number, and greatness and smallness, … It likewise treats of the size and shape of the habitable earth … All this information is secured by means of instruments suitable for these purposes, and by tables and by canons.. For everything works through innate forces shown by lines, angles and figures.