The painting depicts Hayman seated at his easel, working on a portrait of Devis. Hayman is wearing a dark cloak and a white wig, and he is surrounded by various objects associated with his profession, including a palette, brushes, and a portfolio of drawings.
The painting is a testament to Devis's admiration for Hayman, who was one of the most successful and respected painters of the 18th century. Hayman was a founding member of the Royal Academy of Arts, and he was also the Master of the Worshipful Company of Painter-Stainers.
Devis studied under Hayman for several years, and he learned much from his teacher. He adopted Hayman's technique of painting in thin, transparent layers, and he also learned how to create expressive and lifelike portraits.
"Master Simpson" is one of Devis's most accomplished works, and it is a valuable record of his relationship with Hayman. The painting is also a reminder of the important role that teachers play in the development of young artists.