The story "The Sixteen Keys" contains a reference to the "von Horst–Shea" process, whereby a person can maintain a lifelong youthful appearance, at the expense of a much shorter life, and a sudden dissolution at the end of it. This is done by a magical "balancing" of the body's processes, so that no one part of the body wears out before any other. This is a clear reference to the name of, and events in, Oliver Wendell Holmes' poem, "The Wonderful One-Hoss Shay".