"Wordsworth says that poetry is the spontaneous overflow of powerful feelings, and Burns has left us this confession, ‘I have two or three times in my life composed from the wish rather than the impulse, but I never succeeded to any purpose.' In short I think that the production of poetry, in its first stage, is less an active than a passive and involuntary process; and if I were obliged, not to define poetry, but to name the class of things to which it belongs, I should call it a secretion; whether a natural secretion, like turpentine in the fir, or a morbid secretion, like the pearl in the oyster. I think that my own case, though I may not deal with the material so cleverly as the oyster does, is the latter; because I have seldom written poetry unless I was rather out of health, and the experience, though pleasurable, was generally agitating and exhausting."
— A. E. Housman, “The Name and Nature of Poetry,” in Brewster Ghiselin’s The Creative Process