Shift of tone
Letters has been said to exhibit a "model of decline",[21] as the optimistic tone of the early letters is disrupted and the text become increasingly pessimistic; there is a movement from a "joy, pride, wonder" at the spectacle of America,[22] to the "images of the inhuman brutality of slavery".[23] However, there is disagreement over whether this model of decline is produced by James' own disillusionment, or whether it is evidence of Crèvecœur's voice interceding into the narrative;[21] further, critics disagree over where in the narrative the disillusionment occurs, variably placing it in the third, eighth and ninth letters.[24]
Relationship with the environment
Among the most significant and recurring themes of Letters is that of the individual and society's relationship with their environment; the work has been read as an "impassioned, unqualified defense of American agrarianism".[25] The theme appears especially in Letter II, III and in the letters describing Nantucket and Martha's Vineyard, where James' views are expressive of the doctrine of environmental determinism,[26][27] that human growth, development and activities are controlled by the physical environment.[28] Anna Carew-Miller suggests that what the text articulates on this subject is "the [cultural] myth that a man's relationship with the land confirms his masculinity and dignity as a citizen."[29]