Conversation so far:
When did Thomas Eakin's early career start?
1871.
What kind of works did Eakins produce in his early career?
Eakins' first works upon his return from Europe included a large group of rowing scenes, eleven oils and watercolors in all.
What was his most popular early career work?
most famous is Max Schmitt in a Single Scull (1871; also known as The Champion Single Sculling).
What is a Single Scull?
Eakins placed himself in the painting, in a scull behind Schmitt, his name inscribed on the boat.

Question: Why was this a popular painting?
Self-contained rewrite: Why was The Champion Single Sculling a popular painting?