Sin is whatever obscures the soul.

Read in light of Gide’s recurring suspicion of inherited moral codes, the line reframes “sin” away from a list of prohibited acts and toward an inner, experiential criterion. What matters is not transgression against an external law but whatever clouds lucidity, constricts vitality, or blocks the soul’s capacity to perceive and choose freely. The metaphor of “obscuring” suggests dimming or covering over one’s deepest self—through hypocrisy, fear, self-deception, or conformity—so that moral failure becomes a loss of clarity and authenticity. The aphorism thus aligns ethics with spiritual transparency: wrongdoing is whatever makes the inner life less awake, less truthful, and less able to respond to reality.