“Nothing that happens after we are twelve matters very much,” J.M. Barrie wrote nearly a century ago. As the author of “Peter Pan, or the Boy Who Would Not Grow Up” and as a man desperate not to lose his marbles (the glass kind with multi-colored swirls), he was an authority on the challenges of turning into an adult. Once we grow up, Barrie lamented, we are “done for,” and he spent a good part of his life mourning the moment when other children made it clear that he was too old for pirate games.

Growing up is hard to do at any time, but especially in a culture where Bob Dylan and other crooners urge us to stay “Forever Young” and shops trumpet names like “Forever 21.”  In Childhood: Its History, Philosophy, and Literature, a course I have taught for many years now, the most poignant moment in the term comes when I play a sequence from Steven Spielberg’s “Hook,” a 1991 cinematic sequel to Barrie’s “Peter Pan.” There is rarely a dry eye in the lecture hall when one of the Lost Boys contemplates the creases in Robin Williams’s grown-up face and gently reproaches him with the words: “Peter, you promised never to grow old.”

“Hook” never reveals exactly when or why Spielberg’s Peter Banning decides to grow up and become a corporate pirate who turns family man. But in “Tuck Everlasting,” inspired by Barrie’s play, Natalie Babbitt’s character makes it clear that remaining forever young can be a real curse: “I want to grow again . . . and change. And if that means I got to move on at the end of it, then I want that, too.” Readers of “Peter Pan” will know that Peter’s eternal youth comes at the price of memory, along with the cost of love, duty, commitment, and many other weight-bearing words. Neverland may be fun, games, and sport, but it also quickly transforms itself into a Nietzschean dystopia marked by the eternal return of the same. With time, even the “ecstasies innumerable” of Neverland become stale pleasures.

But is the adult world really any better?  In a commencement address at Kenyon College, David Foster Wallace famously declared: “You graduating seniors do not yet have any clue what ‘day in day out’ really means. There happen to be whole, large parts of adult American life that nobody talks about in commencement speeches. One such part involves boredom, routine and petty frustration.”

The Harvard bubble is the best insulator I know against the boredom that so tormented Wallace. In my years at this institution, each term has always delivered on the rainbow promise of fresh new ideas and intellectual surprises.  Graham Greene may have believed that there is nothing to equal the “excitement and revelation” of our first fourteen years, but he evidently also found university life at Oxford “childish and ostentatious.”

As perceptive as David Foster Wallace was in his commencement address, he discounted the boredom, routine, and petty frustration that the most precocious among you have already experienced.  Some of you may be ready to leave, not just Neverland but also the bubble that has sheltered you at Harvard.

And so, off you skip now, like the most heartless things (as Barrie would say), ready to navigate and explore terrain full of challenges that no poet, philosopher, or professor can chart for you. Off you go to the trenches of the real world, where you will get religion—that is, find out what you really want from life, what you will worship, and what will be the object of your devotion.

The real world and its inhabitants will badger you constantly about the value of getting and spending. Few will praise the fringe benefits of failure or remind you of the importance of imagination as J.K. Rowling did at Harvard’s 2008 Commencement. And almost no one will tell you that the consolations of the imagination are not imaginary consolations.

Many years ago, Mark Twain told the young woman who played Peter Pan onstage in New York how much he admired J.M. Barrie’s work. “It is my belief that ‘Peter Pan’ is a great and refining and uplifting benefaction to this sordid and money-mad age.”  Somehow I feel sure that Twain understood the importance of levitation and levity, flight and fancy, and lack of gravity and nimbleness, especially after age 12, when life begins for real, pace J.M. Barrie. And so I will simply close with words spoken some years ago at Commencement ceremonies by Jeremy R. Knowles, then Dean of the Faculty: “Soar like the eagles that you are.” I have just two words to add to his: Never land.

Maria Tatar chairs the Program in Folklore and Mythology.  She is the author of "The Annotated Peter Pan," to be published by W.W. Norton later this year.