Theory of Gravitation

One day in 1665 Isaac Newton was sitting under the apple tree. He was really bored, so he decided to sleep under that tree. When he was sleeping, suddenly the apple fell down of this tree. This apple hit his head. After this, Isaac woke up and looked around. He realized that the apple hit him and he was thinking of why it had happened. On the next day he was thinking about this force which made the apple fell of the tree. In 1680 he knew what the force was and he was writing about it. In 1687 he wrote the book about this force and he named it : Theory of Gravitation.