The axiom know thyself was inscribed on the Temple of Apollo at Delphi. It is worth stating here that Apollo was the Greek God of Reason. This particular temple at Delphi was home to the Oracle of Delphi and the Priestess Pythia, who was known for divining the future and consulted before all major decisions.
The unexamined life is not worth living (Socrates)Tweet
The legend says that 7 sages of Ancient Greece gathered together at the Temple of Apollo and summarized their wisdom in the expression know thyself. This expression has been, however, attributed to several other enlightened minds such as Socrates and Plato.
The idea and importance of knowing yourself is not exclusive of western thought though. The Hindus believed man was not born knowing himself and such activity was rather bold and challenging.
Knowing the Self seems to be a universal quest and a human need deeply carved in our collective unconscious. In Psychology, knowing yourself is crucial for the development of your sense of self and identity. This involves knowing your values, your potential, your purpose in life, and finding healthy ways to express yourself.