BROOK Farm was the most visible, and in some ways most successful, of the many American secular utopian experiments of the 1840s. This decade, as Sterling Delano explains in Brook Farm: The Dark Side of Utopia, † was one of our nation’s most distinctive, infused as it was by the idea of the perfectibility of humanity. Delano’s book is impressively researched but also, through no fault of his own, pretty boring. The “dark side” of the experiment just isn’t very dark, consisting mainly of the community’s chronic inability to achieve financial solvency, as well as ordinary quarrels over organization. Social utopians don’t usually deserve our sympathy, but I put down Delano’s book moved by the genuine decency of these not-so-radical reformers.