The controversy surrounding the historical criticism of the Bible in late nineteenth-century America can be understood by examining approaches to the Bible among Protestant intellectuals between 1820 and 1900. The scholarly study of the Bible lay near the heart of American intellectual life during the nineteenth century, and, for much of the century, learned discourse more or less presumed the timelessness and certitude of biblical revelation. From the early years of the century, the Scottish philosophy of Common Sense armed American theologians with an effective apologetic by which to defend Christianity from the dangers associated with German biblical criticism and other threats. But the weapons of the Common Sense apologetic, ironically, became a stumbling block to many Protestant intellectuals, especially during the second half of the nineteenth century, because its assumptions increasingly pitted the modern disciplines against the older science of the Bible. Responses to the modern disciplines, especially geology and Darwinian evolution, sapped the older Common Sense approach and encouraged concessions among American scholars to historicist approaches, making the menace of German biblical criticism seem real for the first time. After 1870, concerns about the encroachments of philosophical naturalism, associated with Darwinian theory, exacerbated concerns about the naturalistic overtones of historical biblical criticism. These worries sharpened reactions to German criticism among American Protestant intellectuals. As an increasing number of Protestant intellectuals accommodated themselves to the historical, 'scientific' understanding of the Bible, other Protestant intellectuals, maintaining the older scriptural apologetic, attacked these innovations as antithetical to divine revelation. Both sides, however, saw their efforts as defending the Bible's relevance to the modern world. Moreover, these debates provided one of the chief avenues by which historicist assumptions about human culture infiltrated American intellectual life: large numbers of Americans, both the educated and the ordinary, encountered the claims of historicism most directly or for the first time in the arena of conflict over biblical criticism. As a work of history, this project relies primarily on research in the personal papers and published essays of American Protestant intellectuals, especially theologians and biblical scholars in the Unitarian, Congregationalist, and Presbyterian denominations.