This is an image by Robert Mapplethorpe of an orchid in monochrome. The lighting on the orchid outlined the shape of the flower as it stands out from the black backdrop at the back. It is common to use a black backdrop behind an object in light color and this image shows the advantage of doing so.
Moreover, both sides of the orchid are lit while the right side is brighter than the left side. I think the photographer put the light source on the right side (farther than where the orchid is placed) of the object as you can see more details on the right, and uses a reflector on the left side to bounce the light back to the flower as the left side of the orchid appears to be softer and more delicate.
This is an image by Brett Watson entitled “Dune, Oceano” in 1934. It is an image of a dune which is like a small hill in the desert. The light from the side emphasizes on the texture of the sand. Waves of sand form different curves as the wind blows by creating unique texture out of the dune.
While the opposite side of the curves is the part which is under the shade. It is so dark that viewer can hardly see the details within. It creates an illusion that the darker part is a continuity of the waves of sand curves making the image overall flat like on a single surface like it is not a dune at all.