What ends youth, and when? Settle first what youth is. Is it innocence? Strength? Speed? But this is glib. The idea of youth is so fraught, tangled, enmeshed that no systematic approach to it is possible. So I will glance as I may.
Why is it easier to imagine an evil old man than an old evil man?
I can very easily imagine a man who has become evil by becoming old; and what I imagine is something serious and dangerous. But when I imagine an evil man who has become old, what I imagine is pathetic and sad. This is not a modern divagation: the evil old man or woman is an archetype. So too (though not often) is the evil man whom age leaves weak, bereft, and lost.
The same asymmetry obtains between a wise old man and an old wise man; between a kind old man and an old kind man; between a foolish old man and an old fool, &c.
Call this folk gerontology. It seems to teach that old age so divides life that after it we may acquire new traits and retain them vigorously; but that those traits we bear from youth into old age fade and diminish in it. (Note that traits does not include abilities—the type of the Old Master is an exception.) It defines youth to be either a time when we do not possess the qualities that will later distinguish us, or a time when we are distinguished by qualities we are bound to lose.
I see no basis in any kind of fact for this distinction, but the universality of it suggests that it is there to be established.
When does youth end? We have a tribal answer—youth ends with ordeal. We have a a number of civilized answers—youth ends with marriage, vocation, mastery or battle. But none of these formal occasions are satisfactory. Compare a person the day before and the day after, and you will measure no difference.
The notion that youth has a formal end implies a tripartite division of life into ineffectual youth, active maturity, and honorable senescence. Another familiar division is simply into strong youth and feckless eld. I cannot say which is the more natural. The second division matches the general pattern of animals, but the first is more distinctively human (given our prolonged childhoods). The trichotomy is the most common division, but the dichotomy seems agreeable to high civilization—at least to ours and the classical world's.
But our idea of youth and the classical idea of youth are not therefore the same. The phenomenon of formal education, the conceit that children have wisdom in their mouths (if nowhere else), the sense both of the suitability of play to children, and its unsuitability for adults—these give us an idea of youth shyer and more delicate than the robust vision of the ancient world. Alexander conquered the world and was thought young. But being young among the moderns ends as soon as anything happens that has not happened to everyone else. Classical youth was individualizing; modern youth ends with individuation.
Speaking of Alexander, remember that Caesar, at the age of 30 and still unknown, wept because by that age Alexander was already Alexander. But Caesar would get his chance to be Caesar. In the vigor, ingenuity, audacity and arrogance of his later actions the qualities of youth are certain. Yet had a fever taken Caesar that year then his death, had it been marked at all, would have been marked as an old death. So to the question, "Can youth be recovered?", we can answer yes—for a Caesar.
Can you marry and be young? Of course you must be old enough, but can old enough be young? Or does to marry imply a sobriety and commitment that is only mocked by being called young? Or can one have children and be young? Does that responsibility compel youth's end—is youth passed on in making youth?
Without state-of-nature castles in air I note that once you have passed on your genes nature is done with you. Only culture has use for you, while you persist consuming resources without any direct role in the natural order. Nature arranged the habits, abilities and vices of youth toward the end of reproduction. Once that end is fulfilled, nature loses interest. Quote, "The noblest works have proceeded from childless men" (and women); is this because the refusal to get or bear prolongs youth by refusing its consummation?
How seriously should youth be taken? The ancients took youth seriously and expected great things from it. We have two modern views to chose between.
We have youth as the best days of my life, a moment of strength and hope that sets almost before it has risen, our sole fragile chance at bravery, and once over beyond recall even in memory, only to be longed for—when not regretted.
We also have youth as a surfeit of dangerous energy, an unshielded, ungrounded, overcharged capacitor in continuous danger of shorting out, melting down, spinning free—a turbid, turgid, tumid white heat of hormonal drive limping on impaired judgment between transitory moments of release and refractory calm; something we are lucky to survive and would never wish on anyone, let alone ourselves.
This choice is important, because it determines how the rest of life is to be arranged. If youth is the best, then we should aim to be comfortable once we are useless. If youth is the worst, we should aim to be free once we are sane.
Can youth be accurately remembered? Must it incandesce with a rose radiance as it decays to its half-life, or can it be remembered justly as it was? To ask another way: is life necessarily disappointing? Obviously if youth always becomes a retrospective paradise then what comes after will always be a disappointment. At best you can be philosophical, and try to remind yourself that your vision is distorted. But I think it can be remembered justly, though it requires artificial means—old photos to look at, old journals to read, old friends to converse, old shows to rewatch.
What does high school do to people? Listening to those who go—at least to Americans—it seems to have no lasting effect besides trauma and regret, and no benefit beside the war-buddy friendships formed among survivors. It appears as a sort of circular hell, where everyone is damned by someone, and demon to someone else. In trying to think about youth the implodably massive fact of the institution draws everything else into its orbit. Perhaps this is why there is so little good thinking done about youth: people trying to think about youth end up thinking about high school. What would youth look like without this wheel to break on?
How far can the advantages of youth be extended? We are not only animals. By conscious discipline and ingenious technology we have learned to formalize or commoditize generally what life grants only as special advantage. We universalize gifted strength with machinery, gifted memory with writing, gifted health with medicine, &c. (I call this universalizing the index of civilization.)
If youth has any positive content, it must be abstractable. And if we find that youth is not abstractable, then we know that youth has no positive content. But we have had great success—and largely within living memory—with such abstractions. We have established that it is not unnatural or ridiculous that the old should learn, love, and plan as intensely, as bravely, and as hopefully as the young; that the use of technology to extend and preserve physical powers does not defy nature, but serves it; and that community of purpose is as much possible to the old as to the young. More may yet be done.