Contrary to Ionian philosophers who explored the mysteries of nature, Socrates believed that people should only care about things around them. Because nature is created by God, full of God's special will and purpose, and the object of God's wisdom, people can't know it. If people insist on understanding nature, it is an arrogant trespass, and as a result, they can not only know nature, but also know themselves. Socrates quoted the famous words engraved in front of the temple of Delphi to call on people: "Man, know yourself." In his view, philosophy should study issues related to life, such as justice, virtue, courage and piety, instead of focusing on the profound and mysterious nature.