Muse poetry is composed at the back of the mind: an unaccountable product of a a trance in which the emotions of love, fear, anger, or grief are profoundly engaged, though at the same time powerfully disciplined; in which intuitive thought reigns surpalogically, and personal rhythm subdues metre to its purposes.The effect on readers of Muse poetry, with its opposite poles of ecstasy and melancholia, is what the French call a frisson. 

 ....--Robert Graves, 1961 Oxford University lectures

Note: I found the above in the essay, "Gleaning the Unsaid off the Palpable": Seamus Heaney's Response to Slyvia Plath.