A boy of fifteen who is not a democrat is good for nothing, and he is no better who is a democrat at twenty.

The saying contrasts youthful idealism with adult prudence: at fifteen, a lack of democratic sympathies is framed as moral or civic deficiency, while by twenty continued “democrat” zeal is treated as immaturity. In this reading, “democrat” functions less as a modern party label than as a shorthand for egalitarian, popular, or radical sentiment associated with youth. The epigram belongs to a long tradition of political aphorisms about people becoming more conservative with age. However, because the attribution to John Adams is doubtful, the quote’s significance may lie more in how later generations used Adams’s authority to legitimize a cynical view of political maturation than in Adams’s own political thought.