He was... 40 years old before he looked upon geometry; which happened accidentally. Being in a gentleman's library..., Euclid's Elements lay open, and 'twas the 47 El. libri I. He read the proposition. 'By G-,' sayd he (he would now and then sweare, by way of emphasis), 'this is impossible!' So he reads the demonstration of it, which referred him back to such a proposition, which proposition he read. That referred him back to another, which he also read. Et sic deinceps, that at last was demonstrably convinced of the truth. This made him in love with geometry. John Aubrey, A Brief Life of Thomas Hobbes, 1588-1679 (1898) as quoted by Stephen J. Finn, Thomas Hobbes and the Politics of Natural Philosophy