Today’s Daf Yomi page, Eruvin 3, begins with a strange admission: Even though all units of distance are supposed to be precisely the same, the rabbis tell us that there's a happy cubit and a sad one. Historian and author Gil Troy joins us to talk about his latest book, a collaboration with legendary refusnik leader Natan Sharansky, and tell us why some places are indeed inherently happy and some profoundly sad, and what we can do to bring light even to the grimmest of spots, like the Gulag where Sharansky spent nearly a decade. How can Jews help each other to stay in happy places in perpetuity? Listen and find out.