When john Szarkowski said "quoting out of context" he meant we have the ability to choose what the scene will look like we have the option to take out or include whatever we want in a photograph this allows us to change the context.
The public might have been shocked to see realistic pictures because they are not used to this kind of art. Before this time art was very unique and there wasn't much of realistic art it was all interpretation of reality not actual depiction.

I choose this picture because it is a good example of what we are talking about. This is a painting of a scene just like what Degas was doing. Painting by Ralph Goings.