The old, sloping Jewish cemetery in Haditch, Ukraine, is one of those rare windows into the past. Look out from the hilltop, as I did recently, and a vista nearly unchanged in two centuries opens up below. During the winter you'll see a frozen, grassy clearing dotted with barren birch trees descending to the banks of the placid Psel River. There, at the bottom and to the right, sits the original red brick mausoleum of Rabbi Schneur Zalman of Liadi (1745-1812), the Alter Rebbe.