Cambridge University closed down in the summer of 1665 when the plague broke out. New ton,

a student there, went home to Lincolnshire. He stayed home for two years while the disease ran its course in the area around London. The 23-year-old Newton spent that time studying and laying the foundations for his greatest work, the Principia. One day he sat thinking in his garden, when an apple fell. Then he realized that the direction the apple fell, along with every other object on this round earth, was always toward Earth's center. It wasn't just that the apple fell, but that it tried to go to Earth's center. That was Newton's eureka moment. He realized that Earth had drawn the apple to it. He realized that every object in the universe draws every other object— probably in proportion to its mass. Newton didn't publish his Principia until 20 years later. But he formulated the Law of Universal Gravitation (LUG) there in his Lincolnshire garden. He showed us that was true of planets and moons as well.

Now enters a surprising character. The person who popularized the apple story, was none other than the well-known French writer and philosopher Voltaire. Due to his outspoken views, in 1726 he was forcibly exiled to England where he spent the next three years. Newton died in 1727 so Voltaire would have been familiar with the many discoveries made by him. Voltaire was also acquainted with Newton's niece, Catherine Barton. Newton was a bachelor and she had a greed to manage his London home; therefore she would have been familiar with the apple story, which she related to Voltaire.

Voltaire sided with Newton in Newton's bitter fights with Leibnitz. In Candide, Voltaire ridiculed Leibnitz. The character Dr.Pangloss, who went about insisting that we live in the "best of all possible worlds", was Voltaire's version of Leibnitz.

We might chalk Vohaire's apple story up to "partisan license". But it' you've ever done anything creative, you'll recognize the plausibility of the apple story. You'll remember your own moment when some small and commonplace event revealed a great troth to you. That's the way creativity works.

Which of the following is true about Newton's Principia？

A．Newton was motivated to write the Principia after he saw the apple fell.

B．The Law of Universal Gravitation was originally included in the Principia.

C．Newton began to form. the idea of the Principia when he was a college student.

D．The Law of Universal Gravitation was formulated long before the Principia.