Aaron Siskind (1903-1991) began as a documentary photographer but morphed into a darkroom Abstract Expressionist. As this handsome coffee table book shows, the transition was less abrupt than some have thought. In the 1930s Siskind shot protest rallies in Harlem and Bowery Street scenes, but also focused on odd architectural details, shadow play and the curious symmetries of the human landscape. By the ’40s his work often resembled the paintings and collages of the Modernists, but he found his images and symbolic shapes in his lens as he searched through the visual clutter of reality. Siskind was always a careful observer, and as Gilles Mora’s text reminds us, a sympathetic and influential teacher for many years at Chicago’s Bauhaus-inspired Institute of Design.