Henri Rousseau was born the son of a master plumber and ironmonger Julien Rousseau and his wife Eleonore. He began to be interested in poetry and music early on. After finishing school, he served as a clarinetist in an infantry regiment. After his military service, he managed to get employed by customs. Hence its name Le Douanier ("the customs officer").
Henri Rousseau, La muse inspirant le poete, 1909
Kunstmuseum Basel, online collection http://sammlungonline.kunstmuseumbasel.ch/eMuseumPlus 04.09.2019