The natural place of things. 17th century diagram showing the Aristotelian concept that everything has a natural place. The four elements sat one upon the other, with earth at the centre, then water, air and fire. Anything tends to move to its natural place - thus stones sink in water and rain falls while bubbles in water and smoke in air rise. This woodcut illustration comes from Disquisitiones mathematicae by Christoph Scheiner, published at Ingolstadt in 1614.