I went to the press preview of the Guston show at the MFA. Intense, illuminating, fascinating. It is not a conventional retrospective that goes chronologically, exploring, for instance, an artist's various influences, which in Guston's case range from Giotto and de Chirico to Krazy Kat and R. Crumb. Instead, the show is organized to make clear that while his manner of painting changes dramatically over time, his concerns are consistent, lifelong. To wit: Evil lurks in the world, and what is a mere artist to do about it? The only thing he or she can do: keep on painting.