Which writers and thinkers were close friends of Gustave Courbet?

Gustave Courbet, the leader of the Realist movement, maintained close friendships with several prominent writers and thinkers of his time. Notably, he was an intimate of the poet Charles Baudelaire and the social philosopher Pierre-Joseph Proudhon.1

These figures, along with other friends, collectors, and patrons, are depicted in his famous 1854–55 painting, The Painter’s Studio, which serves as an allegory of the influences on his artistic life.12