We are not unlike a particularly hardy crustacean. . . With each passage from one stage of human growth to the next we, too, must shed a protective structure. We are left exposed and vulnerable -- but also yeasty and embryonic again, capable of stretching in ways we hadn't known before. These sheddings may take several years or more. Coming out of each passage, though, we enter a longer and more stable period in which we can expect relative tranquility and a sense of equilibrium regained.