The Darkness (and the light)
There is no background—only darkness. No architecture, no landscape, and so as a result, we focus on the figures who are all located in the foreground of the painting. The spotlight effect of the lighting is very dramatic, and so we have very stark contrasts of light and dark. In other words, where modeling is usually a slow movement from light to dark, here we have very dark shadows right next to areas of bright illumination. The effect is very dramatic.