During this era different areas of science and natural philosophy would take giant steps forward. The exalted French philosopher and athematician René Descartes would publish his Discourse on Method, which complemented his Meditations and which made use of his famous "method of doubt" to try to prove that there actually was such a thing as absolute certainty. This concept would dominate philosophy and science until the present day. Galileo had, just a few years beforehand, published his classic Dialogue Concerning the Two Chief World Systems. This book had proposed the novel and correct idea that it was the sun and not the earth that was the center of the solar system.
But, above all else, the seventeenth century saw the publication of Newton's stately Principia, which begat the science that has come to be called "classical mechanics." Newton brought all this about when he stated in his Principia a number of important principles, the most powerful of these being the law of universal gravitation. In devising it, Newton was trying to answer two fundamental questions: why do objects fall to earth, and what keeps the earth moving?