Baudelaire ascribed exceptional importance to the arrangement of Les Fleurs du mal. His book, he said, constituted "a perfect whole," which he had arranged according to a preconceived plan. One of his earliest readers, the novelist and critic Barbey d'Aurevilly, spoke of a "secret architecture" and "a plan calculated by the solitary meditative poet," though he did not go into details; and ever since, scholars have pursued the question of structure. This new study offers an exciting reading of the 127 poems of the second edition (1861), which shows that, beyond the meanings of its individual poems, the collection has a sense that we ignore at substantial cost. The author presents a precise dialectical method, a "somber and limpid tete-a-tete" of the poet with himself. The argument is pursued between the poems, which ask to be read with and against each other.