Dr. Heidegger attempts to act as a guide for his four guests (unless you interpret his character as malicious, which is also legitimate). Before he offers them the elixir, he warns them:
"It would be well that, with the experience of a lifetime 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!" (19)
Of course, they don't heed his advice. But that's not for lack of his trying.