Meryl Streep as Mother Courage in John Walter’s absorbing, perceptive Theater of War.

There are documentaries that entertain and many more that educate, and there are plenty that grab you by the lapels and spout hummus-breath in your face about how you need to stop eating meat and trade your vulgar, barbarous combustion-powered vehicle in for a bike — today! Then there are the rare documentaries that prod you, subtly but insistently, to reexamine the way you’re living.

John Walter’s Theater of War is one of the latter and no, it’s not about third-world labor practices or animal rights or climate change or the war. Okay, well, actually it is about the war — and all wars— but not directly. What it’s directly about is a 2006 Public Theater production of Bertolt Brecht’s heart-rending play Mother Courage and Her Children. Brecht wrote this tale of the 17th century Thirty Years War during the early part of World War II, and it’s a clarion work of drama so eloquent and prescient that to call it “antiwar” is to reduce it to something duller and more didactic than it is. To paraphrase the novelist and Brecht/Karl Marx scholar Jay Cantor — one the half-dozen major interview subjects who contribute to director/editor John Walter’s complex, absorbing film — the play “is pretty close to a howl of despair.” It tells us not that “war is bad,” but that “war is.”