This section begins with a very brief overview of early medical philosophies leading up to Barker’s time, when science was developing an important place in American intellectual life. There was a gradual increase in the cultural authority of “regular” medical education by preceptorship, didactic medical school lectures, and medical licensure, as opposed to self-help or domestic medicine, sectarian medicine, the Thomsonians, homeopaths, and others. William Cullen, Benjamin Rush, and John Brown influenced medicine at the end of the eighteenth century. Pierre Louis in Paris, who had become a major influence on American medicine during the first third of the nineteenth century, believed that “medicine is a science of observation” and a “rigid method” is essential for medicine to improve. Careful case reports, necessary for practice and teaching, were facilitated by the numerical method. The Physician’s Case Book, published by Allen & Ticknor, Boston, in 1832, was an attempt to help physicians to record and organize their case reports. Possible reasons Barker failed to publish his manuscript include finances, competition from other books, and the rapidly changing medical beliefs during the first third of the nineteenth century. A comparison is made to Noah Webster’s 1832 decision to abandon the revised edition of his 1799 book on epidemics.