what did isaac newton discovered as a mathematician?
isaac newton co-developed calculus with gottfried wilhelm leibniz
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 Newton did have a close friendship with the Swiss mathematician Nicolas Fatio de Duillier , whom he met in London around 1690 . Their intense relationship came to an abrupt and unexplained end in 1693 , and at the same time Newton suffered a nervous breakdown . Some of their correspondence has survived . 

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 Newton 's derivation is found in Section IX of his Principia , specifically Propositions 43 – 45 . His derivations of these Propositions are based largely on geometry . 

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 Starting in 1699 , other members of the Royal Society ( of which Newton was a member ) accused Leibniz of plagiarism . The dispute then broke out in full force in 1711 when the Royal Society proclaimed in a study that it was Newton who was the true discoverer and labelled Leibniz a fraud . This study was cast into doubt when it was later found that Newton himself wrote the study 's concluding remarks on Leibniz . Thus began the bitter controversy which marred the lives of both Newton and Leibniz until the latter 's death in 1716 . 

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 It was while Galileo was under house arrest that he dedicated his time to one of his finest works , Two New Sciences . Here he summarised work he had done some forty years earlier , on the two sciences now called kinematics and strength of materials , published in Holland to avoid the censor . This book has received high praise from Albert Einstein . As a result of this work , Galileo is often called the " father of modern physics " . He went completely blind in 1638 and was suffering from a painful hernia and insomnia , so he was permitted to travel to Florence for medical advice . 

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 Newton himself had been rather more modest of his own achievements , famously writing in a letter to Robert Hooke in February 1676 : 
