Newton on the three-body problem. Book page showing text and a diagram concerning the three-body problem as examined by English physicist and mathematician Isaac Newton (1642-1727). This text (in Latin) includes corollary 17, one of 22 corollaries that Newton wrote in relation to his proposition 66, theorem 26, from book 1 of 'Philosophiae Naturalis Principia Mathematica' (1686). Book 1 of 'Principia' was titled 'Of the Motion of Bodies' (Latin: De Motu Corporum). The three-body problem is the attempt to predict the motions of three bodies using the laws of classical mechanics and gravitation. It is famously difficult to analyse and solve.