What does the Bible say about the thoughts of man?

According to Proverbs 21:4-5, a man's thoughts are crucial in revealing his true nature. The scripture notes that 'the thoughts of the diligent tend only to plenteousness,' suggesting that right, diligent thinking aligns with God's glory. Conversely, the text contrasts this with those born with a 'proud heart,' indicating that without transformation, individuals may be blind to their spiritual impotence and sin. This highlights the importance of inner thoughts over outward appearances, as true attitudes are judged by God who examines the heart, not merely human actions.