Throughout much of the nineteenth century the ascendent star of science was closely tied to the rise of the middle class. Science reflected their optimism and aided them in understanding a world and society in constant motion. The middle class embraced science in a hearty manner and as a labor of love they sought to popularize it in America. By the turn of the century, the middle class enthusiasm for popularization had abated somewhat, but science was still being pursued and popularized with great ardor by others. Only now the group most enamored of science, and certain that its rise was tied to the prestige and power of science, was the socialist movement, the self-appointed sentinel of the working class. No less than the middle class, the socialist intellectuals sought to ground their discourse in scientific language and to make the fruits of science readily available to a wide audience. The great revolutions in science—the Copernican, Newtonian, and Darwinian—became the subject matter for socialist popularizers of science. Their tale was simple: Marxism was a science, a scientific revolution in social thought, that would usher in not only a new world-view, but a new society, a new age.