Charles Le Brun was a major figure in 17th Century French Painting. Here, in his Adoration of the Shepherds (also here), he displays his skill with composition, color and light, using them to gently guide our eye through several aspects of a complex scene.
The immediate focus, of course, is on the mother and child, their illuminated figures accented by the darkened silhouettes of the foreground figures. Our eye then sweeps upward with the rising smoke, through the curves of the angelic banner and out into the heavens which have opened into our scene. When we settle back into the foreground, we have a wealth of other figures, earthly and etherial, on which to focus in turn.
Le Brun’s rich blues and deep orange-reds balance and complement each other beautifully, reinforcing the path of our eye and giving the painting a lively, vibrant character overall.