The moral of the story is to learn from one’s experiences so as not to repeat past mistakes. When Dr. Heidegger invites his friends, Mr. Medbourne, Colonel Killigrew, Mr. Gascoigne, and Widow Wycherly to his study to drink waters drawn from the “Fountain of Youth,” each of them reacts in an almost predictable manner, after drinking off the waters—Mr. Gascoigne gets all political, “ranting about patriotism, national glory, and the people’s right,” Colonel Killigrew gets to ogling Widow Wycherly’s full figure, Mr. Medbourne is all business and talks about “supplying the East Indies with ice” through some strange means, and Widow Wycherly is vanity itself, preening for hours before the mirror. One would expect that, given the chance to be youthful once more, each of Dr. Heidegger’s visitors would tread through life more carefully. It is almost like each one of them is asked the question: if you were to go back in time, would you do things differently? The four subjects have all accumulated a lot of experience about life, and one hopes that they have learned from their experiences. Mr. Medbourne lost all his wealth, in his prime, to a “frantic speculation” and lives like a beggar in his old age. Colonel Killigrew suffers from poor health because of a youth wasted on the “pursuit of sinful pleasures.” Mr. Gascoigne’s brand of politics has driven him into oblivion in his old age, and Widow Wicherly lives a “secluded” life, having involved herself in scandalous relationships with the wrong kind of men.
It is important to note Dr. Heidegger’s statement as he fills the glasses of his four friends: “For my own part, having had much trouble in growing old, I am in no hurry to grow young again. With your permission, therefore, I will merely watch the progress of the experiment.” The doctor knows that “growing young again” has its problems. This is why he carefully selects the subjects of his experiment, ensuring that each has a yearning for youthfulness. He would like to observe, however, if they are willing to redeem themselves from past mistakes, given the chance.