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Isaac Newton by Godfrey Kneller, 1689

Isaac Newton (4 January 1643 – 31 March 1727) an English mathematician and physicist who is especially remembered for his two monumental books Principia Mathematica Philosophiae Naturalis and Opticks. In his Principia, he presented his theory of Universal Gravitation and the three laws of motion, laying the groundwork for Classical Mechanics.


Newton was born on January 4, 1643 in Woolsthorpe, Lincolnshire. His father, a prosperous farmer also named Isaac, died a few months before his birth, and when his mother remarried, Newton was left in the care of his grandparents. His mother returned a few years later, and after finishing school in Grantham, he entered Cambridge University in 1661, where he studied mathematics, physics and astronomy. In 1665, a plague forced him to leave Cambridge and move back to his family home. During this time, he developed the basic concepts for much of his future work, later calling these years „the prime of my age for invention“. After returning to the university, he was elected a Fellow of Trinity College in 1667 and Lucasian Professor of Mathematics in 1669. Two years later, he was elected a Fellow of the Royal Society and became President in 1703, a position he held until his death. In 1687, after years of intense labour and exchange with leading intellectuals of his era, he published his Principia Mathematica Philosophiae Naturalis, considered one of the most influential scientific books of all time. In 1696, he moved to London as Warden of the Royal Mint, becoming Master of the Mint in 1699. His second major work, Opticks, appeared in 1704, and the following year he was knighted in Cambridge. He died in 1727 at the age of 84, having become an international celebrity and the pre-eminent scientist of his time. However, as became only known in the 1930s, Newton devoted a lot more time to alchemical and theological research than to physics or mathematics.


Social Interactions

Newton seems to have shown an aggressive and unsocial behavior in his boyhood. In a list of sins assembled in 1662, he admits having beaten his sister and others, as well as having threatened his parents to burn down their house. Later in life, his aggressions must have eased, and he is not reported as having particularly unpleasant behavior as an adult. On the contrary, Humphrey Newton, his amanuensis for five years, wrote shortly after Newton's death that he experienced the latter as having been „of sedate & even Temper ... without Anger, Peevishness or Passion“,[1] and William Stukeley, one of his first biographers, remembered having seen him laugh often, and said that he possessed „a natural pleasantness of temper“.[2] However, he was also considered reclusive, and until late in life, he kept a small circle of acquaintances, usually staying in the company of a few close friends like the Swiss mathematician Fatio de Duillier or his half-niece Catherine Barton. His difficulties with social relationships continued throughout his whole life, and he doesn't seem to have ever been involved in a romantic affair with a man or woman. According to Humphrey Newton, he devoted himself completely to his studies, going to bed late and eating little, often absorbed in thought and careless about the things around him. These and other personality traits have led psychologist Simon Baron-Cohen[3] to speculate that Newton could have had Asperger's syndrome, an attribution that can still be found in many popular science books.

Fear of Criticism

An often noted characteristic of Newton's personality was his remarkable fear of criticism, which resulted in a hesitation to publish new works. Although Newton developed his version of the Calculus earlier than Gottfried Wilhelm Leibniz, he only published his work in 1704, twenty years after Leibniz's publication. This led to a bitter controversy between Leibniz and Newton over priority for the method, which continued until Leibniz's death in 1714. When fellow Royal Society scientist Robert Hooke claimed that Newton learned the inverse-square law of gravity from him, Newton felt deeply offended and threatened to stop working on the third book of the Principia. It was due to the diplomatic skills of Edmond Halley that Newton continued working, but he didn't publish his new book Opticks until Hooke had died. William Whiston, Newton's successor to the Lucasian chair at Cambridge, described his precursor as of the „most fearful, cautious and suspicious temperament“.[4] Researchers like Sula Wolff[5], Anthony Storr[6] or Hershman and Lieb[7] brought forward the argument that he could have suffered from manic-depression, and David F. Horrobin[8] sees schizotypal tendencies in Newton's behaviour.

Mental Breakdowns

Newton suffered at least two mental breakdowns during his life. The first one occured in 1678, after an intense argument with Robert Hooke and one year before his mother died. The second one, in 1693, seems to have been even more severe, and Newton experienced insomnia, loss of appetite and paranoid delusions that led to him sending strange and attacking letters to friends and colleagues. In a letter to Samuel Pepys, he stated that he felt „extremely troubled“ by the „embroilment“ he was in, and reported not having eaten or slept well in the previous twelve months. He also moaned about not having his „former consistency of mind“.[9] After his recovery a few months later, he apologized to his friends and returned to work as before. However, the incident may have had lasting effects on Newton's psyche, as Hershman and Lieb have argued.[10] Some authors have attributed the breakdown of 1693 to metal poisoning due to alchemical experiments,[11] as high levels of mercury have been found in hair from Newton's corpse after exhumation. However, the poisoning theory has been questioned by others,[12] partly because he showed few of the common symptoms.

Relationship to Mother

Newton grew up without his father, who died a few months before Isaac's birth. What was probably worse, his mother Hanna Ayscough left her son in the care of his grandmother in order to marry Barnabas Smith, a man Isaac felt deep hatred for. She only returned to Woolsthorpe in 1653, when Isaac was ten years old. By then, the young man had already discovered his intellectual talent, but Hanna wanted him to become a farmer as his father had been and took him from school. Luckily, he turned out to be a failure as a farmer, and soon returned to Grantham to continue his studies. The abandonement by his mother may have had a traumatizing effect on young Isaac, and some, like Milo Keynes, have argued that his intellectual ambitions were partly due to his need to regain self-esteem.[13] To Frank E. Manuel[14], Newton's mother was the overshadowing figure in his life, and a sort of oedipal complex accounts for many of his character traits. For example, Manuel thinks that Newton's theological ambitions and anti-trinitarian beliefs developed because he longed for the love of God instead of his mother's and saw Christ as a rival. In his alchemical writings, he often referred to himself als Ieova sanctus unus (Jehovah, the Holy One), an anagram of his latin name.


Newton never married and there are no credible records that he was ever involved in a romantic relationship. This has led commentators to reason that he led a life of complete chastity.[15] Voltaire stated that Newton „had neither passion nor weakness“ and that he „never went near any woman“.[16] One of the accusations that Newton made towards John Locke in the letters following his breakdown of 1693 was that Locke wanted to „emboil [him] with women“.[17] Frank E. Manuel and others argued that Newton could have been homosexual,[18] and linked his problematic emotional life to the guilt he felt. He exchanged friendly and tender letters with Fatio de Duillier, and his breakdown followed the abrupt end of their friendship in 1693. Accordingly, some have speculated that Newton had romantic interests in the young mathematician. In his report of sins, Newton lists „Having unclean thoughts, words, actions and dreams“, as well as two „relapses“, the nature of which is unknown.[19] Furthermore, he wrote about the chastity of monks of the Eastern church in one of his theological writings, and explained their „struggle with incontinent thoughts“.[20] This was seen as partially autobiographic by Manuel.[21] However, due to the lack of evidence, the true nature and extent of Newton's sexuality must be considered unknown.


  • Baron-Cohen, Simon. The Essential Difference: Men, Women and the Extreme Male Brain, Allen Lane, 2003
  • Christianson, Gale E. In the Presence of the Creator: Isaac Newton and His Times, New York, Free Press, 1984
  • Gjertsen, Derek. The Newton Handbook, Routledge Kegan & Paul, 1987
  • James, Ioan Mackenzie. Asperger's Syndrome And High Achievement: Some Very Remarkable People, Jessica Kingsley Publishers, London, 2006
  • Keynes, Milo. The personality of Isaac Newton, 1995
  • Keynes, Milo. Balancing Newton's mind: his singular behaviour and his madness of 1692–93, 2008 (Online)
  • Krull, Kathleen. Isaac Newton, 2007
  • Manuel, Frank E. A Potrait of Isaac Newton, Cambridge, Belknap Press of Harvard University Press, 1968
  • Westfall, Richard S. Never at Rest: A Biography of Isaac Newton, Cambridge University Press, 1983


  1. Keynes 2008
  2. Ibid.
  3. Baron-Cohen 2003
  4. Force, James E. William Whiston: Honest Newtonian, Cambridge University Press, 2002
  5. Wolff, Sula. Loners: The Life Path of Unusual Children, Routledge Chapman & Hall, 1995
  6. Storr, Anthony. Isaac Newton, British Medical Journal, 291: 1779–1784, 1985
  7. Hershman, D. Jablow; Lieb, Julian. Manic Depression and Creativity, Prometheus Books, 1998
  8. Horrobin, David. The Madness of Adam and Eve: How Schizophrenia Shaped Humanity, Bantam Press, 2002
  9. Turnbull, Herbert Westren (ed.): The Correspondence of Isaac Newton, Vol. III, Cambridge University Press, 1961
  10. Hershman/Lieb 1998
  11. Keynes 2008
  12. Christianson 1984
  13. Keynes 2008
  14. Manuel 1968
  15. Gjertsen 1987
  16. Ibid.
  17. Ibid.
  18. Manuel 1968
  19. Gjertsen 1987
  20. Ibid.
  21. Manuel 1968