Colin Marshall talks to novelist Joshua Cohen, author of Cadenza for the Schneidermann Violin Concerto, A Heaven of Others, and now Witz. The new book follows the cross-country (and international, and possibly even interplanetary) journey of Benjamin Israelien, born with a beard and glasses, already nearly a grown man. After a Biblical plague on Christmas Even 1999, Benjamin becomes the last Jew on Earth. He’s first celebrated, then marketed, then turned upon.