Roger Bacon (c. 1214-1294) was a Franciscan friar and an English philosopher. As a natural philosopher, or scientist, he was an early advocate for the use of experimental science. While Bacon did his most outstanding work in the field of optics, he was a strong supporter of mathematics, describing it as “The door and key to the sciences.” The Specula mathematica is a collection of his writings on the uses of mathematics in various other disciplines such as astronomy, music, and geography. The book was compiled and published in 1614 by Johannes Combachius, a fervent Aristotelian, and is considered extremely rare.

On pages 26 and 27 of Specula, Bacon discussed perpendicularity.

The Special Collections staff at the Linderman Library of Lehigh University in Bethlehem, Pennsylvania, is pleased to cooperate with the Mathematical Association of America to exhibit this and other items from the Library’s holdings in “Mathematical Treasures.” In particular, Convergence would like to thank Lois Fischer Black, Curator, Special Collections, and Ilhan Citak, Archives and Special Collections Librarian, for their kind assistance in helping to make this display possible. 

You may use these images in your classroom; all other uses require permission from the Special Collections staff, Linderman Library, Lehigh University.