The apple of his eye, c.1666
It's rootin' tootin' fruitin' Newton again
In the last Histories, we met Isaac Newton’s secretary, a relative of some sort by the name of Humphrey Newton, who reminisced about the great scientist shortly after his death as a contribution to the first intended biography. We saw Newton (1642–1727) described as the archetypal absent-minded professor, forgetting to eat, waking up in yesterday’s clothes… but also a likeable character despite a reputation for austerity. He loved the garden next to his lab, Humphrey reported, and indeed enjoyed a bit of fruit…
In winter time, he was a lover of apples, & sometimes at a night would eat a small roasted quince…
In fact, we also know the the younger Newton even felt guilty for his apple habit – at least when in church. The Fitzwilliam Museum in Cambridge has a fantastic notebook Newton kept in the 1660s, which includes various lists of sins he had committed. In one 1662 list, when he was 19 or 20, he enumerated 49 different sins. Here are some of my favourites:
Eating an apple at Thy house.
Making a mousetrap on Thy day.
Squirting water on Thy day.
Making pies on Sunday night.
Wishing death and hoping it to some.
Having unclean thoughts, words and actions and dreams.
Stealing cherry cobs from Edward Storer.
Denying that I did so.
Setting my heart on money, learning, pleasure more than Thee.
Punching my sister.
Falling out with my servants.1
What a nasty piece of work, eh? (His sister might have thought so, anyway.)
But let’s go back to the fruit theme. Fourteen years later, in 1676, thirty-something aspiring country gentleman Newton was discussing cider-making in letters to his friend Henry Oldenburg, another early member of the Royal Society, and got very exercised by what sort of apple varieties he should plant:2
Sir, — I have now made what inquiry I can into the state we are in for planting, and find there are some gentlemen that of late have begun to plant, and seem to incline more and more to it, but I cannot hear of any professed nurseryman we have. Our gardeners find more profit in cherry trees, and so stock their ground almost wholly with them… But in order to promote the design, I am desired to inquire what sort of trees your friend can furnish us with, at what rates, which way they can most conveniently be conveyed to so great a distance, and what may be the charges of carriage. Also, whether they are to be sent in scions or grafts; the first being more convenient for carriage, and so rather to be wished, unless those trees be found best which are grafted on their native soil…
But, upon discoursing with people, I find we lie under one great difficulty; which is an opinion generally taken up here, that Red Streaks (the famous fruit for cider in other parts) will not succeed in this country. The tree thrives well here, and bears as much fruit, and as good to look as in other countries; but the cider made of it they find harsh and churlish, and so this fruit begins here to be generally neglected… For which end give me leave to make these queries: — What sort of fruit are best to be used, and in what proportion they are to be mixed, and what degree of ripeness they ought to have? Whether it be material to press them as soon as gathered, or to pare them? Whether there be any circumstances to be observed in pressing them? or what is the best way to do it?
OK OK, I’ve picked these apple quotes to clunkily lead into the subject of Newton and one particular apple, of course. We all know the story: he was sitting under an apple tree, one fell on his head and Eureka! there was the catalyst for him developing his equation for describing gravitational force. But this must be apocryphal, right?
It seems not. For one thing, there is still an actual tree at Woolsthorpe Manor in Lincolnshire, the house where Newton was born, and it might be the same tree (of the variety Flower of Kent, apparently a little pear-shaped and rather flavourless) that he allegedly sat under in the 1680s, or at least an offshoot of it as some stories say the original was lost in 1820 (although Newton’s old school, the King’s School in Grantham, has also claimed that the tree was moved to the headmaster’s garden there…). Trinity College, Cambridge, meanwhile, where he worked, has a descendant of that tree outside, planted in 1954. So we have a tree, at least.
The story of the apple is often attributed to being reported by the antiquarian William Stukeley – I mentioned before that he was a friend who wrote a biography of Newton in 1752 (first published in 1936). Stukeley recalled a chat with Newton on this subject on 15th April 1726, when the scientist was an old man:
After dinner, the weather being warm, we went into the garden, & drank thea [tea] under the shade of some apple trees, only he, & myself. Amidst other discourse, he told me, he was just in the same situation, as when formerly, the notion of gravitation came into his mind. Why should that apple always descend perpendicularly to the ground, thought he to himself; occasioned by the fall of an apple, as he sat in a comtemplative mood: Why should it not go sideways, or upwards? but constantly to the earth’s center? Assuredly, the reason is, that the earth draws it. There must be a drawing power in matter & the sum of the drawing power in the matter of the earth must be in the earth’s center, not in any side of the earth. Therefore does this apple fall perpendicularly, or toward the center. If matter thus draws matter, it must be in proportion of its quantity. Therefore the apple draws the earth, as well as the earth draws the apple.3
And we have an earlier source: last time I also mentioned John Conduitt, another friend who was the first to collect biographical info (including Humphrey’s account) shortly after Newton’s death. In the first draft of this collection, from mid-1727, Conduitt noted:
In 1664 he bought a prism to try some experiments upon Descartes’s book of colours & soon found out his own hypothesis & the erroneousness of Descartes’s. About this time he began to have the first hint of his method of fluxions & in the year 1665 [other versions say it was 1666] when he was retired to his own estate on account of the plague, he discovered his system of gravity – he took the first hint of it from seeing an apple fall from a tree…4
(We think of the 1665 ‘Great Plague’ as being in London, but in fact in Cambridge was also hit and hundreds died there. Newton’s seclusion in Lincolnshire was certainly productive – in the two years he spent there, he also developed his method of calculus and conducted optical experiments.)
The earliest published account we know of is from the French philosopher Voltaire.5 He lived in Britain between 1726 and 1729 (in exile after a dispute with a powerful French nobleman), and in 1727 he made this passing reference in ‘An essay on epick poetry’:
And thus in our days Sir Isaac Newton walking in his gardens had the first thought of his system of gravitation, upon seeing an apple falling from a tree.6
In 1733, Voltaire elaborated slightly in his Letters Concerning the English Nation (later republished as Philosophical Letters). There we read:
But being retired in 1666, upon account of the Plague, to a solitude near Cambridge; as he was walking one day in his garden, and saw some fruits fall from a tree, he fell into a profound meditation on that gravity, the cause of which had so long been sought, but in vain, by all the philosophers, whilst the vulgar think there is nothing mysterious in it.7
Voltaire mentions elsewhere that he had met Newton’s niece, Catherine Barton Conduitt (John’s wife), and she is presumed to be the person who shared the story with him.
And that’s as far we know – was Newton himself romanticising the story as an old man, 60 years after it happened? Perhaps, but it feels plausible, and perhaps he saw an apple falling when he was already pondering these questions, and it just helped a bit – today’s scientists seem to prefer the idea that he had immersed himself in the question of gravity over a long period. Incidentally, the version of the story that says it fell on his head was entirely made up by the writer Isaac D’Israeli (father of the later prime minister Benjamin), who wrote “one of the fruit fell, and struck him a smart blow on the head” in his 1791 essay ‘Poets, Philosophers, and Artists, Made by Accident’. That title reminds us that in a way the Newtonian apple story opens up a bigger can of worms about the nature of inspiration: can it really come in a flash, or is it midwifed by long reflection beforehand?
You can see all this in Stukeley’s original handwriting here (I have modernised slightly), thanks to the Royal Society.
Probably: but there is another passing reference in 1727 by the philosopher Robert Greene, in Latin that translates as ‘This famous opinion has its origin, as is commonly reported, from an apple’.