The meaning of this quote by Walt Whitman relates to Whitman's communal, inclusive, and all-embracing ethos.

In his preface to his poetry collection Leaves of Grass, Whitman states, "The American bards shall be marked for generosity and affection and for encouraging competitors." In other words, Whitman wants American poets to be kind, welcoming, and good to one another. Poets in the United States shouldn't view each other with suspicion. They're not rivals or opponents. Poets are on the same team, so they should treat one another with care and consideration and try to bring out their best qualities.

The statement from the preface applies to Whitman's overall ethos. In his poems, Whitman regularly articulates themes tied to inclusion and community. He supports something like a universal perspective where everyone is on equal footing and no one is discriminated against for any reason. For example, in "Song of Myself" (a long poem published in Leaves of Grass), Whitman's opening three lines read:

I celebrate myself, and sing myself,
And what I assume you shall assume,
For every atom belonging to me as good belongs to you.

This famous first stanza reflects the ethos in the quote. As in the excerpt from the preface, Whitman is promoting a type of unconditional camaraderie and community. Whitman seems to want everyone—bards, workers, women, men, and so on—to get along, support one another, and recognize their common humanity.