Know thyself

आत्मानमनभिज्ञाय
विवेक्तुं योऽन्यदिच्छति ।
तेन भौतेन किं वाच्यम्
प्रश्नेऽस्मिन् को भवानिति ॥

One aspires to understand the world without knowing self. What does such a person answer to the question 'Who are you?'

Know thyself.