An early woodcut made in 1963, Joan Snyder was in her first year of grad school, signals the themes of the painter’s life’s work. She made “Portrait of Emily’’ the night John F. Kennedy was assassinated. Deeply gouged and starkly black and white, it captures sorrow and horror on the face of the teacher with whom she heard the news. It’s a remarkably accomplished woodcut portrait for one so young. An echo of German Expressionism, it captures grief’s power with detailed nuance. Yet it’s nothing like what we have come to think of as a Joan Snyder work. “Dancing with the Dark: Joan Snyder Prints 1963-2010,’’ a survey organized by the Zimmerli Art Museum