Different artists teach you different things. Bonnard simplified things, removing them partly from their naturalistic context. His simplifications are of one order. There could be other ways to do it. Like Domenico Veneziano’s way, for instance. But they point to and teach how to use parts of things: how you can use fragments of experience to call forth memories and lead thought into an area behind experiences — like seeing the back of a tapestry.
You have to see things before you can paint them. Bonnard teaches a different way of seeing the world by taking it apart, thing by thing. Every artist that you really begin to understand does something similar by showing the world through a personal experience of it. It makes no difference if the artist is old or new. The discoveries of the old artists are still new, they are connected to life, and the world itself is still in its first bloom of youth.