Never was there, perhaps, more hollowness at heart than at present, and here in the United States. Genuine belief seems to have left us.

While Whitman is aware that the United States has come out of the Civil War materially powerful and prosperous, he fears the moral and intellectual life of the Unites States is lagging behind the quest for material goods and prosperity.

I hail with joy the oceanic, variegated, intense practical energy, the demand for facts, even the business materialism of the current age, our States. But wo[e] to the age or land in which these things, movements, stopping at themselves, do not tend to ideas. As fuel to flame, and flame to the heavens, so must wealth, science, materialism—even this democracy of which we make so much—unerringly feed the highest mind, the soul.

In the above quote, Whitman is saying, using high minded language, that material wealth, while good, is not the highest good. It should only be fuel to a flame—in other words, the means to an end. That end should be not simply getting richer, but using our wealth to develop our minds and souls. Anything less betrays America's democratic ideals.

In the prophetic literature of these States (the reader of my speculations will miss their principal stress unless he allows well for the point that a new Literature, perhaps a new Metaphysics, certainly a new Poetry, are to be, in my opinion, the only sure and worthy supports and expressions of the American Democracy,) Nature, true Nature, and the true idea of Nature, long absent, must, above all, become fully restored, enlarged, and must furnish the pervading atmosphere to poems, and the test of all high literary and esthetic compositions. I do not mean the smooth walks, trimm'd hedges, poseys and nightingales of the English poets, but the whole orb, with its geologic history, the kosmos, carrying fire and snow, that rolls through the illimitable areas, light as a feather, though weighing billions of tons.

Not surprisingly, the poet Whitman sees in poetry the way to both expand and redeem the American spirit. Whitman advocates for a poetry that will break away from its English and European predecessors and find its own voice. That voice sounds very much like Whitman's own poetic voice: a poetry not of the domestic vista—what he calls the "smooth walks, trimm'ed hedges" of the English—but a poetry that encompasses the grandeur of the entire cosmos.