Hats Are The Enemy of Poetry

What could "Hats are the Enemy of Poetry" possibly mean? Absurdly, it invites the reader to put on her thinking cap. Or better, to go bareheaded into the book, the first poem of which is entitled: Emily Dickinson is not in. Please leave a message. What message? The reader will decide, as always. But at the least, she will be exposed to the elements. "Before hummingbirds, Sweetheart, /there was plutonium," as the final poem in the collection begins, ending "in the garden of a God/ we do not, cannot, comprehend, / for what seems more than/ an instant, but less than eternity."