Soon abandoning his law training, Gras published Lei Carbonièrs (The Charcoal Burners), a rustic epic poem in twelve cantos, in 1876, noted for its "elemental passion" and scenic descriptions, for which he gained immediate recognition.

In 1879, he married the niece of Joseph Roumanille, the husband of his sister Rose Anaïs.

His next work, Tolosa, an epic poem about the invasion of the Albigenses by Simon de Montfort, came in 1882, to further acclaim.

He produced a volume of short poems, Lei Romancèras Provençals, in 1887, followed by a collection of prose stories, La Papalina, in 1891.

It was praised by former British prime minister William Gladstone, and was subsequently published in several other languages.