Definition of Irony
The story begins with an introduction of the principal cast of characters in language that implies social respectability and wisdom. But then the narrator undercuts this implication in an ironic twist:
THAT very singular man, old Dr. Heidegger, once invited four venerable friends to meet him in his study. There were three white-bearded gentlemen, Mr. Medbourne, Colonel Killigrew, and Mr. Gascoigne, and a withered gentlewoman, whose name was the Widow Wycherly.
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:
Unlock with LitCharts A+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.