“Wordiness for Kiefer is painterliness,” writes the historian Simon Schama. “The library and the gallery, the book and the frame inseparable, even interchangeable, in his monumental archive of human memory.” Given Anselm Kiefer’s long list of philosopher heroes, the idea that he might have become a philosopher of time is not implausible. Kiefer’s Becoming the Ocean, a painting featured in this retrospective in St. Louis, is like a plane that is about to ditch itself in the sea at high speed; underneath and within human time, it takes on all the important difficulties that come with this kind of inquiry. Kiefer’s paintings do not have the kind of ethereal leverage over history that a painter like Jacques-Louis David is comfortable with. Instead, they are philosophically in the thickets in the style of a modernist writer, doubtful and mortal. The artist’s first U.S. retrospective in 20 years, “Becoming the Sea” takes rivers as its central metaphor. The show features a giant site-specific installation inspired by the Mississippi and Rhine Rivers. —Jimmy Lux Fox