Why Did Isaac Newton Never Marry?

Newton was not married. That much is certain. He lived for 84 years and left behind an enormous archive millions of words of correspondence, notebooks, and manuscripts and not one line of it contains anything resembling a romantic attachment. No love letters. No broken engagements. No references to a woman (or anyone else) in tones that suggest anything beyond professional or collegial regard.

There is one partial exception. A niece of Newton's, Catherine Barton, lived with him in London for many years and was reportedly the mistress of Charles Montagu, Earl of Halifax, who was Newton's patron. Whether Newton approved, arranged, or was simply indifferent to this arrangement tells you something about his relationship with conventional social life, though historians disagree about what exactly.

The closest thing to a biographical account comes from William Stukeley, who interviewed Newton in his old age and recorded various recollections including the apple story. Stukeley describes Newton as retiring and solitary but does not dwell on his romantic life, perhaps because there was nothing to dwell on.

There is a version of this story where the explanation is simply: Newton was too busy. He worked extraordinary hours, rarely left his rooms, and during his most productive periods allegedly forgot to eat. His colleague Humphrey Newton (no relation) observed that he 'seldom went to bed till two or three of the clock, sometimes not till five or six.' A man on that schedule is not attending many dinner parties.

But 'too busy' is probably too simple. Plenty of scientists have been devoted to their work and still managed marriages Hooke, Boyle, Halley all had social lives of varying complexity. Newton's solitude goes beyond a scheduling problem. It reads more like a fundamental preference: he found the company of ideas more congenial than the company of people, and he organised his life accordingly.

What we can say with confidence is that Newton never expressed regret about his unmarried state in any document that survives. He also never expressed contentment about it. Like most things in his inner life, he kept it entirely to himself.