"'Know Thyself’ was written on the forecourt of the Temple of Apollo at Delphi. Legend tells that the seven sages of ancient Greece, philosophers, statesmen and law-givers who laid the foundation for western culture, gathered in Delphi to inscribed ‘know thyself’ at the entry to its sacred oracle. The adage subsequently became a touch-stone for western philosophers, and extended its reach as the influence of Greek philosophy expanded."
"When asked what was the most difficult thing, Thales replied, 'To know thyself.'
When asked what was easiest, he replied, 'To give advice.'"
If men would search diligently their own minds, and examine minutely their thoughts and actions, they would be more cautious in censuring the conduct of others, as they would find in themselves abundantly sufficient cause for reproof."
"The adage also teaches us to set a proper value upon ourselves, and to be careful not to do anything that may degrade us. It is not known to whom we are indebted for this golden rule; we only learn that it is of very long standing, and was held in such high estimation by the ancients, that it was placed over the doors of their temples, and it was also supposed by them, that 'E coelo descen- dit,' it came down from heaven.' 'Man know thyself!' tins precept from on high Came down, imagined by the Deity; Oh! be the words indelibly imprest On the live tablet of each human breast."
And now you know also! :)