What does the famous French photographer Nadal's work "Self-portrait of Nadal" reflect?

It is worth noting that with the help of the famous French photographer Nadal, the first Impressionist Art Exhibition was held in the former site of his photo studio. Nadal was an influential portrait photographer at that time, and he was good at depicting the psychological characteristics of characters. For example, Nadal's Self-portrait is Nadal's self-portrait. The picture highlights the movements of both hands, which leads to the head center of the picture-an eye opposite to you seems to be the window to the soul, which fully shows the depth of expression that photography can deeply depict the psychological characteristics of characters.