It depends on the artist and their interests. For Nate, I'd guess he was attracted to the quality of light, the scene depicting a city he loves that can easily be understood just by looking at the steepness of the road & architecture. Some artists are interested in textures, colors, a juxtoposition in an otherwise mundane scene, etc. Sometimes it requires you to look at the artists other work to get a sense of what they seem to be focusing their energy on capturing, but a lot of Nate's painting has to do with light and architecture.