In Hawthorne's "Dr. Heidegger's Experiment," the reader can assume by the title of the story that the doctor is not completely certain what effect the drink will have on the three men and the woman who have joined him on this auspicious afternoon.
It becomes just that as the men and the widow are given the very elixir of life, that with each drink returns them to their youth—something each desperately misses. Each lives an existence now that is the result of a youth ill-spent, and Dr. Heidegger warns them to approach this experiment with wisdom born of experience.
"Before you drink, my respectable old friends," said he, "it would be well that, with the experience of a life-time to direct you, you should draw up a few general rules for your guidance, in passing a second time through the perils of youth. Think what a sin and shame it would be, if, with your peculiar advantages, you should not become patterns of virtue and wisdom to all the young people of the age!"
The doctor has already declined to drink himself, saying that growing old has been a difficult process and he would not have to go through the difficulty of growing young again, but...
I will merely watch the progress of the experiment.
So poised only to be an observer, the doctor watches as the four elderly people drink of the Fountain of Youth, people who find it ridiculous that "they should ever go astray again."
However, as they repeatedly drink and grow younger, all of the very things that plagued their elder years return with their youthful vigor. It is obvious that they have learned nothing from their mistakes and stand prepared to make them all over again. They all fight over the now-lovely widow, and each man plans to pick up the life and business practices of his youth that led each to his downfall. The widow, once more, finds her personal value rests primarily upon in her appearance and the renewed desire all three men have to win her favor—as had obviously happened in the past.
As the men struggle over the woman, they become physically aggressive and knock over the table with the vase containing the old rose and the magical water. Even as the life of the rose fades, so does the youth of the four members of the experiment. As the test comes to its conclusion, the doctor is able to observe that the folly each pursued in youth is something they will continue now to pursue, as they all declare that they will immediately take a "pilgrimage" to Florida to find the magical water and drink it every day, all day long.
As for Dr. Heidegger, we can assume that he had contemplated taking the water himself. The reader will recall that he lost his young love the day before they were to be married. He has lived with that loss his entire life. It would seem that the difficulties that have brought him to this point in his life are things he does not wish to relive or extend.
"Yes, friends, ye are old again," said Dr. Heidegger; "and lo! the Water of Youth is all lavished on the ground. Well—I bemoan it not; for if the fountain gushed at my very doorstep, I would not stoop to bathe my lips in it—no, though its delirium were for years instead of moments. Such is the lesson ye have taught me!"
We might infer that the wisdom of the years has not been wasted on the doctor. We can also infer that he was hoping to gain knowledge from the experiment, and has done so in observing a lesson they have shared with him. He was originally unwilling to drink the liquid himself, so we may assume that he had reservations about it from the first. It is safe to assume that he was concerned that drinking himself might create in him the desire to make the same mistakes all over again that he had when he was a young man.
It would seem that the doctor's concerns were well-founded. These people will not "become patterns of virtue and wisdom to all the young people of the age," as the doctor had hoped might be the experiment's outcome. We might also infer that Dr. Heidegger knows he would not have fared any better, regardless of his good intentions.