Depends on what you mean by"modern poetry." He does not write modernist verse, like T. S, Eliot, who is closer to being the founder of modern poetry, but he is a daring experimenter (broke decisively from the French Alexandrine, although one of his most memorable poems, "Le bateau ivre," is written in it). He wrote prose poems and was not afraid of discontinuities (which Eliot certain picked up on); he wrote in the symbolic mode common to much modern poetry. Every modern poet has read him, and some of the lines and effects stay with a reader long afterward.
Moreover, Rimbaud more or less stopped writing when he was 21 or so. (There is some dispute about the age at which he ceased and the sequence of the composition of his poems.) He stopped at his peak. Apart from a few early verses--in themselves remarkable--there are no bad or uninteresting poems by Rimbaud. The saga of his life is as moving and spectacular as that of people like Oscar Wilde, Scott Fitzgerald, and Sylvia Plath, and his very best poems ("Le bateau ivre," "Sonnet des voyelles," "Mémoire," "L'aube," "Les chercheuses de poux," "Les poètes de sept ans," even "Le dormeur du val" (it is hard to know where to stop) are oases, are pieces of linguistic paradise. Whether he is the "founder of modern poetry" or not--I suspect not--he is a very great poet, whose works transport and enchant, even when they repel and disgust.


