The funerary representation of Prince Philippe, who died at 16. Sculpted ca. 1264:
The Four Ages of Learning, ca. 1300:
Youthful Recreation (ca. 1300):
A Young Squire (ca. 1300):
Size is also status. Musicians (ca. 1300):
Young Saul, from Images de la vie du Christ et des saints (ca. 1280-1290):
Gawain bidding goodbye to Arthur and Gueneviere (ca. 1425):
The dance of Salome (ca. early 13th Century):
A Youth and a Maiden (ca. 1499-1502):
analepsis 
While reading, “Emblems of Youth,” and looking at these images on this blog post I was thinking about what are some of the main ideas and nuances that surround today’s image of youth.
One concept I notice is this idea of like, “eternal youth” and “forever young.” I think a lot of society (in terms of American society but this can be said for other cultures) is fascinated and intrigued by youth and looking “young” for as long as possible. The example you gave in the first day of class of the clothing store “Forever 21” is a great example. You see young girls and women of all ages in this store adopting this standard “youthful” look. Come to think of it, there’s a reason why it’s called “Forever 21” ^_^
Many are not only trying to gain a youthful appearance through clothing. Many people are having a great amount of plastic surgery to stay young for as long as they can. People are obsessed with having youthful physical appearances and many women and men develop this Dorian Grey Syndrome.
Though vying for “eternal youth” is a concept that I feel has always been valued and hold to importance among different generations and looked at differently among a variety of cultures. Like what is written in the essay, “People tried to preserve it for as long as possible, as evidence by numerous recipes for beauty preparations, healthy diets, and the struggle against aging.”
Something that also interested me in the essay was when Pastoureau wrote how a young virgin girl was described particularly in the Middle Ages.
“…of warm and moist complexion, she was “clean in heart and body,” pure “as the iris of an eye”; she was simple and “not talkative, with a fine countenance and delightfully dressed”; her soul was timid and shy, because she was ” a virgin in the greenness of her age.”
This description reminds me of the character Lolita and how the main character Humbert in the novel was fixated on her because of her “purity.” I think a lot of people equate “youth” with “purity” and “purity” with “youth” which of course is not always the case but looking at these images I sort of sense this enchantment of youth and purity (like, not being affected by such a cruel world, that sort of purity).
The expansion of the youth category goes both ways, though. Those who are older want to be younger– “30’s the new 20!”– even as the very young want to be perceived as more mature but still youthful. My example for the latter are figures like (the rapidly aging) Miley Cyrus and “tween” fashions.
The trope of young female purity runs pretty deep, I agree. Excessively, even pathologically, so. There was a fairly commonly accepted idea in the 18th and early 19th centuries that sex with a young virgin had healing properties– it could cure syphilis! What’s interesting to me is the way that that youthful purity is both elevated and and at the same time the object of prurient interest. Maybe that explains Humbert Humbert’s unwholesome fascination with Lo.
Funny you mention Miley Cyrus, I tend to think about the old Calvin Klein adds with a 15-year-old, Brooke Shields with the message, “Nothing comes between me and my Calvins.” Very lolita-esque. I do see this trend among very young girls (well the media’s representation of young girls) as a person wanting to be taken as serious as an older women but still hold a youthfull quality