Dr. Heidegger is pretty much the polar opposite of his four guests. While they resent their old age and are eager to grow young again, Heidegger maintains that he has "had much trouble in growing old" and is "in no hurry to grow young again" (17). While they romp about in youthful folly, he sits back "with philosophic coolness" and observes (25). Most importantly, Heidegger learns a lesson from his experiment, while his four guests are as ignorant as ever. See "What's Up with the Ending?" for more on that thought.