It always falls down. That's how the apple helped Isaac Newton.

它总是垂直下落——苹果正是这样启发了艾萨克•牛顿。

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In this photo taken Friday, January 15, 2010, Royal Society librarian Keith Moore holds the manuscript of 'Memoirs of Sir Isaac Newton' by William Stukeley, pointing to the word 'gravitation', in London. An 18th-century account of how a falling piece of fruit helped Isaac Newton develop the theory of gravity is being posted to the Web on Monday, Jan. 18, 2010, making scans of the fragile paper manuscript widely available to the public for the first time.

An 18th-century account of记账 how Newton developed the theory of gravity was posted to the Web Monday, making the fragile paper manuscript原稿，手稿 widely available to the public for the first time.

Newton's encounter with the apple ranks among science's most celebrated² anecdotes奇闻轶事, and it can now be read in the faded cursive script草书，草写体 in which it was recorded by William Stukeley, Newton's contemporary同时代的人.

Royal Society librarian Keith Moore said the apple story has resonated共鸣，共振 for centuries because it packs in停止 so much — an illustration插图，说明 of how modern science works, an implicit⁴暗示的，含蓄的 reference to the solar system and even an allusion⁵ to the Bible.

When Newton describes the process of observing a falling apple and guessing at the principle behind it "he's talking about the scientific method," Moore said.

"Also the shape of the apple recalls the planet — it's round — and of course the apple falling from the tree does indeed hark back回归原处，回想 to the story of Adam and Eve, and Newton as a religious man would have found that quite apt有倾向的，恰当的."

The incident occurred in the mid-1660s, when Newton retreated to his family home in northern England after an outbreak of the plague瘟疫，灾祸 closed the University of Cambridge, where he had been studying.

Stukeley's manuscript recounts a spring afternoon in 1726 when the famous scientist shared the story over tea "under the shade of some apple trees."

Stukeley wrote that Newton told him the notion of gravity popped into the scientist's mind as he was sitting in the same situation.

"It was occasion'd by the fall of an apple, as he sat in contemplative沉思的，冥想的 mood. Why should that apple always descend⁶ perpendicularly直立地，垂直地 to the ground, thought he to himself ... Why should it not go sideways, or upwards⁸? But constantly to the earth's center?" Stukeley wrote. "Assuredly, the reason is, that the earth draws it. There must be a drawing power in matter."

Stukeley's account on the Royal Society's Web site joins notes from Newton's 17th-century scientific rival Robert Hooke — documents that were lost for several hundred years before their recent discovery in a house in England.