It has been touted as the greatest painting ever done by an American artist, but when it was first shown at the 1875 Centennial Exhibition, it was considered a scandalous piece not even worthy of inclusion in the art exposition. Instead it was hung in the out-of-the-way medical pavilion nearby.1,2 The nearly life-size portrayal of Professor Samuel D. Gross pausing to lecture in the middle of a surgical case is Thomas Eakins' signature masterpiece (Figure 1). Alongside it one could hang his second piece on the same subject, this time with Professor D. Hayes Agnew in the lead role, painted 14 years later (Figure 2). The differences between the two are subtle but important. The key significance lies in the fact that the 2 works were painted more than a decade apart and at a crossroads in medical history when antisepsis was first introduced to the surgical mainstream. In no small part due to their creator's obsessive adherence to painting reality as it was, which therefore gives a sense of factuality seldom possible in painting, Eakins' Clinics bring to life a remarkable moment in the history of surgery.