What allegory is found in this excerpt from Nathaniel Hawthorne's "Dr. Heidegger's Experiment"?

In truth they had. The Water of Youth possessed merely a virtue more transient than that of wine. The delirium which it created had effervesced away. Yes! they were old again. With a shuddering impulse, that showed her a woman still, the widow clasped her skinny hands before her face, and wished that the coffin-lid were over it, since it could be no longer beautiful.

"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!"

But the doctor's four friends had taught no such lesson to themselves. They resolved forthwith to make a pilgrimage to Florida, and quaff at morning, noon, and night, from the Fountain of Youth.

Answers:

Youth is eternal.
Old age can be a curse.
Age does not equal wisdom.
Precious things should not be wasted.
Wisdom comes with age and experience.