The truest greatness lies in being kind, the truest wisdom in a happy mind.

The line contrasts conventional measures of achievement—status, intellect, or power—with inward and ethical standards. “Greatness” is redefined as kindness: a social virtue expressed in how one treats others, not in public acclaim. “Wisdom” is likewise shifted from mere knowledge to a “happy mind,” suggesting emotional balance, gratitude, and a disciplined optimism. Read together, the couplet argues that the highest human attainments are accessible and practical: moral generosity and cultivated inner well-being. It fits the moralizing, inspirational strain often associated with late-19th/early-20th-century popular verse, where character and attitude are presented as the foundations of a good life.