Among the countless achievements of Isaac Newton, any number of which would have made him a houseold name on their own, his articulation of the force of gravity in the late 17th century surely ranks near the top. The legend of Newton's inspiration coming from a falling apple is often dismissed as apocryphal, but the great physicist's memoirs would seem to indicate otherwise.
A biography written by William Stukeley, one of Newton's contemporaries, relates the apple story as Newton himself told it to Stukeley. The text of Stukeley's Memoirs of Sir Isaac Newton's Life has long been available online, but the Royal Society opened up digital access to the handwritten manuscript itself Sunday.
"After dinner, the weather being warm, we went into the garden and drank thea [sic], under the shade of some apple trees," Stukeley wrote. "[H]e told me, he was just in the same situation, as when formerly, the notion of gravitation came into his mind. It was occasion'd by the fall of an apple, as he sat in contemplative mood. Why should that apple always descend perpendicularly to the ground, thought he to himself…"
Stukeley's work was not published until 1752, a quarter-century after Newton died at the age of 84, so it's possible that his recollection of Newton's tale veers somewhat from the truth. But the legend also appears in other accounts of the time, so if the apple-tree story is a tall tale, it's one nearly as old as Newton's theory itself.
Title page of Stukeley's 1752 manuscript: The Royal Society