When he had found out that it was universally true he wrote down all his ideas, checking carefully to make sure that he had not made any errors. Then he did a very strange thing. He put all this work away and did not tell anyone about his discoveries. Various explanations have been put forward to explain Newton's reasons for not telling the world, but in reality no one really knows why he did this. Some say he was worried about the fame it would bring, as he greatly valued his privacy. In fact, he kept this wonderful discovery secret for 20 years, finally publishing the complete theory in Principia Mathematica in 1686. This book caused great controversy. The church felt that the order in the heavens was created by God and man should leave such matters alone. The general scientific community found it difficult to believe that gravitation could be affecting things at such distances with no connections between them. Questions such as 'Where are the ropes pulling these planets together?' were asked.