In classic Whitman style, Democratic Vistas attempts to cover the vast range of human experience from a timeless perspective. This volume is Whitman's attempt to synthesize his ideas into art theory. Naturally this theory includes economics, politics, science, history, etc. because Whitman is a naturalist. He desires to place his ideas within the greater context of the universe. While his arguments pertain to a specific place and time and people, he argues from a cosmic perspective.
Faced with the dramatic changes of the States after the Civil War, Whitman devotes serious consideration to the future of the nation. He recognizes the pros and cons of frontier development and industrialization. He also explores in depth the political climate, landing upon a form of ideal democracy as his goal. In response to the divisive violence of the previous decades, he's eager to impart a unifying set of ideals behind which the general public can unite. He warns that if no unity is achieved, the forward momentum of democracy will come to a crashing halt, any potential of the American experiment wasted.
Whitman's art theory, then, proposes the artist's responsibility in such a climate. He believes literature is the true method of persuasion by which people may come to understand the greater significance of their democracy. He seems to think that America could become some sort of utopia, an ideal nation. As an artist, however, he feels compelled to participate in the shaping of that progress. Rather than sacrifice the goal for the process, he's willing to interfere with the natural order somewhat in order to influence the human mind. He views the progress of the soul as supremely important, allowing for -- and even advocating for -- adjustments of the mind in order to serve this purpose. This is the role of the artist, in Whitman's perspective.