Man in frock coat, Reverse glass painting early 19th century

Delightful, delicate Reverse glass painting depicting a man in a frock coat reading in an interior, like a shadow play.
On the wall, a painting or a window opening onto a landscape


A painting under glass is an image painted directly on one side of the glass.
on one side of the glass, with the result seen on the other. The image is thus inverted.
The challenge: anticipating details, shadows and light.
We start with the foreground, then move on to successive planes until we reach the background: the final stage, which covers the entire glass surface.