At its heart, Hawthorne's story of four once badly behaved elderly people recapturing their lost youth for a "transient" moment is a morality tale—although Hawthorne deftly leaves the readers in the dark as to the truth of what the doctor's "experiment" really is. When he presents the friends with the image of the rose entering the water, we might imagine that his experiment is: will this water have the same effect on humans as it has been determined to have on flowers? As the story progresses, however, the doctor's wry comments make us wonder if this was really the experiment at all—particularly when, at the end, he states that he would not touch the Fountain of Youth even if it were available to him.

In truth, the experiment seems to be this: if people were able to become young again, would they have learned a lesson from the experience of having lived for so many years? In the end, the four guests who have drunk from the Fountain have not learned this lesson: they simply want to go to Florida, find the fountain, and "quaff" from it constantly. They have not observed, as the doctor has, how foolishly they behaved under the influence of youth. Their passions inflamed and their youthful follies reawakened, the guests become belligerent, competing over the woman they once loved, exactly as they did when they were really young. Hawthorne's conclusion seems to be that foolish people do not really learn anything from their past mistakes, but will repeat them if given the opportunity.

Another interesting question Hawthorne leaves open in this story is this: does the fluid really make the guests young again, or is it simply the power of suggestion? On the one hand, we know that they have observed themselves in the mirror and seen young faces, even claimed to have the weight of their years lessening as time goes on. But when the long mirror in the study catches a glimpse of them, it sees them as old people behaving ridiculously. We could interpret this as emphasizing the point that youthful behavior is excused in the young, but if we saw older people behaving in this way, it would be clear how ridiculous and damaging it is. It may also indicate that only age and the sense of being old and tired can ever stop fools from behaving foolishly—underlining Hawthorne's moral still further.

Is there really something magical in the water? Hawthorne deliberately leaves this question open-ended and draws many parallels between the effects of the Fountain of Youth and alcohol. Dr. Heidegger pours the water into champagne glasses, and his guests note its near-carbonated appearance. It’s almost as if the liquid is champagne itself. The lively and youthful twist in the previously tame party is “not unlike what might have been produced by a glass of generous wine.” There are little hints throughout the story that suggest the guests at this gathering have been fooled by alcohol. It is implied that alcohol consumption releases inhibitions in the same way that youth might, and should perhaps be treated with caution.