Writing back in 1888, Adolf Neubauer, the father of modern scholarship on the Lost Tribes, warned that “It would be lost time . . . to trouble ourselves about the identification of this stream.” Neubauer was referring, of course, to the Sambatyon River, the mythical waterway that, according to common understanding, rests each Sabbath and separates missing Jews—the ten lost tribes or others—from their brethren, and indeed from the known world. Six days each week, according to the legend, the river runs so powerfully that neither these tribes nor their seekers can cross it; on the Sabbath, either natural wonders or halakhic restrictions prevent them from doing so as well. Thus, whether showcasing the sheer power and solemnity of the seventh day or the piety of the isolated (or general) community, the Sambatyon legend certifies that only in the messianic age will this lost population be restored to the rest of the Jewish people.