is perhaps the most elusive of all poetic forms as it lacks any formal definition, unlike a haiku or a sestina, which can make it identifiable. Although like most other forms, the prose poem became naturalised in English through translation and inspired reading of foreign literature.
An obscure French book called Gaspard of the Night, by Louis Bertrand, is widely acknowledged as the first instance of prose poetry. Grotesque, gothic and macabre, the book made a strong impression on Baudelaire, whose poetry is replete with juxtapositions of the vile and the beautiful, the vulgar and the lofty, the downright despicable and the grandiose, so relentlessly practiced in The Flowers of Evil that the categories finally fuse and become inseparable.
Concomitantly with that defining work, Baudelaire wrote a book of “little poems in prose” called Paris Spleen, now available in a noteworthy translation by Keith Waldrop. In the dedicatory preface to Paris Spleen, Baudelaire describes his work and the idea of a prose poem thus: “Which of us has not, in his ambitious days, dreamt the miracle of a poetic prose, musical without rhythm or rhyme, supple enough and striking enough to suit lyrical movements of the soul, undulations of reverie, the flip-flops of consciousness.”
These fifty short pieces spanning a variety of genres from narrative to meditative, parable to fantasy, litany to essay, form the definitive collection of modern prose poetry. It was Paris Spleen and not The Flowers of Evil that inspired Rimbaud to produce yet another startling work in the form: Illuminations.
 Two pieces from which can be read here: