A digression from my series on the geometric point

 

Although Euclid’s axiomatic system obviously dominated all geometrical thought at this period, the Geometria Speculativa by Thomas of Bradwardine (c.1290-1349) departed from Euclid in several important respects, and continued to be read throughout the seventeenth century. This particular edition (Zurich ETH-BIB Rare 2351q) was printed in Paris on 6 March 1511 and was extensively annotated, presumably at some point after 1643. Notice that the reader corrected the text to agree with the diagrams in the Second Conclusion, thus allowing the underlined statement ergo duo anguli primi smil sunt equales (…) to be the case.