Lewis Cass, a literary critical predecessor to Mark Twain, criticized Cooper in 1826 and 1828 in the North American Review, the same magazine that Twain later published his vehement attack on Cooper in 1895. Cass had had "official relations" with Indians in Michigan and asserted that this experience made him able to critique Cooper and Heckewelder's idealization (Pearce 211). A common subject of Cass' attack was Cooper's heavy reliance on Reverend John Heckewelder's (1743-1825) popular Native American studies, including An Account of the History, Manner, and Customs of the Indian Nations who once Inhabited Pennsylvania and the Neighboring States (1819).
In his book, The Indian in American Literature, Albert Keiser asserts: "General Lewis Cass, Governor of Michigan territory claimed in his 1828 attach that Heckewelder had
surveyed the character and manner and former situation of our aboriginal inhabitants under a bright and glowing light. His account is a pure, unmixed panegyric. The most idle traditions of the Indians with him become sober history; their superstition is religion; their indolence philosophic indifference or pious resignation; their astonishing improvidence, hospitality; and many other defects in their character are converted into corresponding virtues." (106)
Cooper came to the defense of Heckewelder, and by association, himself, and challenged Cass in his 1850 Preface to the revised Deerslayer edition that "Cass had not known the Indians at their best and, more important, that he was writing the sort of romance in which effects had to be heightened and colored to register as poetically true" (Pearce 211).