This summer, friends and I took a cruise in Alaska where the tourist shops often featured the Russian matryoshka dolls. The dolls originated in Japan but were made popular in Russia around the time of the Russian Revolution, a century ago. You've seen them -- you pop open an outer doll, and nested inside is another. The magic of the art is that you keep opening layer after layer, only to find another even smaller doll, until at last the final incarnation is just a kernel in size. The successive dolls vary from near exact duplicates with hard-to-identify slight...