What 19th century realist artist said "Art cannot be taught."?

Answer 1

“The old schools of art were unable to produce this unity; how could they, since art cannot be taught. They must be merged once more with the workshop.”

by Walter Gropius, Bauhaus Art Movement, Germany, 1919

Germany had just lost World War One and the Bauhaus was at its heart a very anti-academic movement. It was centered on doing the work.

I am unable to find a 19th century artist who says that art cannot be taught. Maybe an American like Winslow Homer ?

Answer 2

Art cannot be taught, art can only be sought.
Lani Picard
though she is neither a realist, nor 19th century