Dr. Heidegger's elderly acquaintances are quite convinced of their transformation and behave like raucous young people, mocking the Dr. Heidegger's age, dancing, flirting with each other, and fighting. As all of this plays out, Hawthorne hints at a sense of dramatic irony by turning attention at one point to a mirror that suggests (with its reflection) that the four friends haven't actually become youthful—the mirror shows them as they were before they drank the water from the Fountain of Youth, and this creates some dramatic irony, as readers begin to sense that the transformation these people have undergone isn't as comprehensive as they'd like to think:
Yet, by a strange deception, owing to the duskiness of the chamber, and the antique dresses which they still wore, the tall mirror is said to have reflected the figures of the three old, gray, withered grandsires, ridiculously contending for the skinny ugliness of a shrivelled grandam.
Hawthorne highlights the gap between the characters' perception of themselves as carefree adolescents and the reader's growing suspicion that the transformation is illusory. This is one of many small details in the story that seems to cast doubt upon (but never completely refutes) the supernatural qualities of Dr. Heidegger's elixir. From the perspective of the mirror, the scene looks quite different: four elderly people "ridiculously" imitating the conduct of the young. The narrator, with great irony, refers to the scene reflected in the mirror as a "strange deception," despite the heavy implication that it is precisely their feeling of youth that is deceptive.
