Tombereaux de boue" are vehicles loaded with garbage, and "boue" is a mixture of filth kneaded with earth and water, found in both Jonathan Swift and Marcel Proust. The "décrotteurs" are often depicted (Carle Vernet, Louis Boilly), and Mercier devotes a chapter to them, recalling that Lutetia comes from lutum, "mud". Baudelaire's mud is what remains of the garbage after the passage of successive rag-pickers, to be sold as fertilizer to the market gardeners of the faubourgs. Bourbe" is the height of it all, insoluble and terrifying - in Les Misérables, Jean Valjean almost drowns in it; it's also the name of a former prison turned maternity hospital for destitute women, where the narrator of L'Âne mort finds the fallen heroine, close to the hospice des Enfants-Trouvés.
The same mud can be found in a poem by Prarond that was wrongly attributed to Baudelaire, "Un jour de pluie" (1841), and which has been likened to La Fanfarlo. It is present in the earliest poems in Les Fleurs du mal, such as "Le Crépuscule du soir" and "Abel et Caïn", as well as in "Tableaux parisiens". In "Perte d'auréole", again, a halo falls into the slush, recalling the topos of treasure found at the corner of bollards, and ends up on a picker, recalling the ragpicker-sovereign of "Vin des chiffonniers". One character recommends "having this halo displayed", certainly above a bollard. In his book Des classes dangereuses de la population dans les grandes villes et des moyens de les rendre meilleures, Honoré-Antoine Frégier evokes the myth of the silver cover picked up at the corner of the bollard. During a performance of Le Chiffonnier de Paris, by the republican Félix Pyat, on February 26, 1848, the day after the revolution, Larousse recounts that Frédérick Lemaître, playing the ragpicker and taking inventory of his basket, found a crown that day.
The cliché associating mud and gold can be found in Baudelaire's isolated verse: "J'ai pétri de la boue et j'en ai fait de l'or." We don't need to see this as an allusion to alchemy, even though it may have been associated with chiffonnage by Champfleury or Hugo; Baudelaire instead alludes to chiffonnage or "ravage", as does Hugo in a letter to Paul Meurisse. In an early version of "La Mort des artistes", Baudelaire was already playing on the kneading of mire to draw out the ideal; in a draft epilogue to Les Fleurs du mal, we find a variation of the formula, addressed to Paris: "You gave me your mud and I made gold out of it." It's the same mud in which we "trample" and "get entangled" in the other poems.
