“Cave of Forgotten Dreams” crosses Discovery-channel type documentary with philosophizing art house cinema. While not as gripping as his earlier “Grizzly Man,” it is similarly a canvas for German filmmaker and eccentric Werner Herzog’s ruminations about life and death, man and nature. Here, he is given rare access to film the Chauvet cave in France, rediscovered in 1994 after being completely sealed off by a landslide for 30,000 years. The natural formations of the cavern are spectacular but the real star is the paintings of prehistoric mammals, rendered with amazing vitality and sophistication. Long sections of the movie are devoted to simply filming the art in changing light. Herzog doesn’t dwell on the motivations of the painters, declaring them unknowable, and instead focuses on the abyss of time between us and them. In one section of the cave, carbon dating reveals two similar paintings were completed almost 5,000 years apart, a seeming instant for the artists but an incomprehensible gulf for us. The movie was filmed in 3D, to better capture the art on the cave’s undulations and ridges, and while it still worked in the conventional 2D, I wish I had seen it in its intended format. Herzog closes with an odd, whimsical coda about mutant albino crocodiles invading the cave, which didn’t make much sense but reminds us the film isn’t journalism but a personal vision, and he’s showing us the world as he sees it.