What Newton did during the plague

In the summer of 1665, the Great Plague struck London. Cambridge University closed and sent its students home. Isaac Newton, 22 and just graduated, returned to his family’s farmhouse at Woolsthorpe in Lincolnshire.

With no teachers and no lectures, he worked alone for about eighteen months. In that time he developed the foundations of calculus, used a prism to show that white light is made of all the colours, and began thinking about gravity.

Newton later told the story of watching an apple fall in the garden and wondering whether the same force that pulled it to the ground could reach as far as the Moon. The apple probably didn’t hit his head, but the tree is real, and it still grows at Woolsthorpe.

He kept most of it to himself for years. Principia, the book that set out his laws of motion and universal gravitation, wasn’t published until 1687. Historians call 1666 his annus mirabilis, his “year of wonders”. Solitude did not slow him down. It gave him room.