This essay returns to F. O. Matthiessen’s off-handed mention that the book he never wrote was “The Age of Fourier.” The essay reads Harriet Beecher Stowe and Margaret Fuller through this lens, recasting two authors who tend to be used as representative presences on syllabi (Stowe the Sentimentalist, Fuller the Feminist) into a new narrative of radicalization via the utopian socialism of Fourier and US Fourierism. The essay turns to the arts of editorial assemblage, used by both authors to craft their texts, in order to discern the collectivities they wished to build, as well as how they build their texts to propel the ongoing momentum needed in the long durée of movements for social change.