The proverbs of a nation furnish the index to its spirit and the results of its civilization.

Holland argues that a people’s everyday sayings—proverbs, maxims, and folk wisdom—are not trivial ornaments of speech but condensed records of collective experience. Because proverbs circulate widely and persist over time, they reveal what a society habitually praises, fears, excuses, or condemns. In that sense they function like an “index”: a quick reference to underlying moral assumptions and social priorities. The second clause links this moral-psychological “spirit” to material and institutional development (“civilization”), implying that cultural progress leaves traces in language. The quote invites readers to study vernacular speech as evidence for national character and historical change.