In this poem, the speaker/poet reflects on what it is like to write poetry, to be a poet, and how uncomfortable it is. Many of the poet's word choices reflect his sense of vulnerability and the pain associated with this work. His secrets, he says, "cry aloud." We cry aloud when we experience severe pain from some source. Whether it is emotional or physical, we cry when something hurts us. He describes the "anguish" of revealing truths in his work and how his nakedness provides a "shield"—as though he requires protection against the intense openness he must cultivate in order to write. Further, he says,
My heart keeps open house,
My doors are widely swung.
The poet must make of himself, he suggests, an open house, keeping himself susceptible to all emotion—perhaps especially "anger" and "rage," which he describes later—and to all spiritual truths, so that he is able to reveal them to others. Further, he can have no secrets of his own, because they are all revealed by his work.
In this same vein of vulnerability and painfulness, the speaker says,
I'm naked to the bone,
With nakedness my shield.
This sense of vulnerability feels bone deep figuratively, but these words also conjure up a more literal image of an individual being flayed "to the bone"—deeply and horribly wounded. At the same time, the speaker claims that his nakedness is like a shield. Perhaps the only protection he has is his complete and total acceptance of this vulnerability; he wears this vulnerability as a badge of honor, perhaps: a sign of his sacrifice to his art.
In the final stanza, the speaker seems to describe the way the truths he reveals in his work seem to come from outside himself, to come up through himself in some spiritual, mystical process:
The anger will endure,
The deed will speak the truth
In language strict and pure.
The anger is not his anger, the deed not his deed, but rather they bubble up through him, using him as a conduit, and he must receive and transmit this truthful language. He must use these truths and emotions and words to "stop the lying mouth" of others who might wish to hide truth instead of revealing them, as he does. It is, it seems a labor of love, as he says in the first stanza, but that makes it no less "agon[izing]," as he ends the poem.