The greatest happiness for the thinking man is to have fathomed the fathomable, and to quietly revere the unfathomable.

The saying contrasts two domains: what human reason can genuinely comprehend (“the fathomable”) and what remains beyond it (“the unfathomable”). Goethe frames intellectual fulfillment not as conquering all mystery, but as a balanced posture: rigorous inquiry where inquiry is possible, coupled with quiet reverence—humility, awe, restraint—toward what exceeds human grasp. The “thinking man” is happiest when he neither abandons reason for superstition nor inflates reason into omniscience. The line thus expresses a characteristic Goethean moderation: knowledge pursued to its limits, and a dignified acceptance of limits without cynicism or despair.