From an Artsy.net online article:

Eakins’s ambitious painting brought Renaissance-era virtuosity to the mid–19th century United States, as American art was still struggling to find its place on the world stage. The Gross Clinic, which still hangs in Philadelphia today, is a triumph of composition, light, and shadow. 

In 1875, Thomas Eakins decided to paint a picture that would glorify his hometown of Philadelphia. The first ever World’s Fair to be held in the United States, the Centennial International Exhibition, would open in the city the following year. Through his painting, Eakins hoped to honor the scientific breakthroughs that were coming out of the local Jefferson Medical College. The artist observed live procedures by the celebrated surgeon Dr. Samuel Gross, then translated them onto a large-scale canvas that he titled Dr. Gross (1875) (now known as The Gross Clinic). The work has become perhaps the most important painting in the history of American art.

To read more: https://www.artsy.net/article/artsy-editorial-thomas-eakinss-the-gross-clinic-american-painting