The exact measure of the progress of civilization is the degree in which the intelligence of the common mind has prevailed over wealth and brute force.

Bancroft frames “civilization” not as material prosperity or imperial power, but as a moral-political achievement: the displacement of coercion ("brute force") and plutocratic influence ("wealth") by broadly shared public reason ("the intelligence of the common mind"). The “exact measure” suggests a yardstick for judging societies—how far ordinary people’s informed judgment, education, and civic capacity shape institutions and outcomes. Implicit is a democratic ideal: progress occurs when authority rests less on money or violence and more on collective intelligence expressed through law, deliberation, and self-government. The quote also warns that societies can regress if wealth or force again dominate public life.