Poetry is that art whereby the poet arranges imaginary propositions, and adapts the deductions, with the result that he can make a little thing appear great and a great thing small, or cause good to appear in the garb of evil and evil in the garb of good. By acting on the imagination, he excites the faculties of anger and concupiscence in such a way that by his suggestion men's temperaments become affected with exultation or depression; whereby he conduces to the accomplishment of great things in the order of the world.