A common misinterpretation views this passage literally as advice on physical eyesight or health, ignoring its metaphorical intent tied to the preceding context of treasures in heaven versus earth; others reduce it to mere positive thinking or optimism without recognizing the spiritual battle against covetousness, or apply 'evil eye' superstitiously as protection against curses rather than Jesus' warning about the blinding effects of a greedy heart that corrupts one's entire moral and eternal outlook.
Matthew 6:23
King James Version (1769)
23 But if thine eye be evil, thy whole body shall be full of darkness. If therefore the light that is in thee be darkness, how great is that darkness!
Jesus uses the metaphor of the eye as the lamp of the body to illustrate that a person's spiritual condition hinges on their inner focus and perspective; a 'single' eye, aligned with God's kingdom and generosity rather than earthly treasures, fills one's entire being with light and clarity, while an 'evil' eye—characterized by greed, envy, or self-centeredness—plunges the whole life into profound darkness, emphasizing the all-encompassing impact of misplaced priorities on one's soul.