He did all of this in pursuit of a particular kind of treasure, and he’s found plenty. Lansky’s treasure was any book written Yiddish, the language of generations of European Jews. When he started looking for Yiddish books, experts estimated there might be about 70,000 still in existence. Since then, the MacArthur Genius Grant recipient has collected close to 1.5 million books, and he’s finding more every day.