AMHERST, Mass. – They’re not the “Mona Lisa” or “Whistler’s Mother,” but images such as the Cat in the Hat, the Very Hungry Caterpillar and other icons of illustrated children’s books are gaining respect in highbrow art circles.

Once seen as fun but forgettable, the genre is now being featured in mainstream museums and dissected in college art courses.

And as respect for children’s book art grows, the money follows. Buyers are purchasing the illustrations as investments and philanthropists are stepping up, as in the case of the Eric Carle Museum of Picture Book Art in Amherst, which recently received a $1 million gift, its largest donation since it opened in 2002.

Some experts say the reason is simple: More art lovers are recognizing that whimsy and significance aren’t mutually exclusive.

“It’s undervalued as an art form. The great children’s book artists are drawing from art history and the trends of their times,” said H. Nichols B. Clark, director of the Carle Museum, which features numerous artists and houses pieces from Carle’s decades-long career, including his signature Hungry Caterpillar.

“What is especially wonderful about these illustrations is that in this art form, the playing field is leveled. Sometimes the child has more to say about the image than the adult,” he said.

Money can be a touchy subject among art enthusiasts, some of whom question whether inspiration can be tarnished by commercialization.

But some experts say a sure sign of a genre’s acceptance is when museums, collectors and philanthropists willingly open their wallets for it, which is increasingly the case with picture book art.

“You can quibble about the critical side of the art, but the market is bearing out that yes, original children’s book artwork is getting out there,” said Timothy Young, an author on the topic and curator of Yale University’s Betsy Beinecke Shirley Collection of American Children’s Literature.

Illustrated children’s books have long filled the bookshelves of American homes, ranging from Dorothy Kunhardt’s simple “Pat the Bunny” touch-and-feel books to the “wild things” of Maurice Sendak’s imagination or Leo Lionni’s fanciful “Alexander and the Wind-Up Mouse.”

The advent of modernism in the early 1900s caused some to start viewing picture book illustrations as moneymaking frivolity, not serious art that could stir the soul. Art that was realistic became viewed as less important, Clark said.

Yet even as they were excluded from the mainstream, children’s book illustrators often embraced the same trends as other artists, from art deco to surrealism to Warhol-style pop art.

“These artists were in touch with their peers and influenced by them, even if person ‘A’ was doing kids’ books and person ‘B’ was doing adult stuff,” said Young, the Yale curator. “You can often see the common influences if you compare pieces from the same period.”

The book illustrations also often reflected social changes, adding cultural significance to the art.

Ezra Jack Keats’ 1962 book, “A Snowy Day,” for example, was among the first mainstream children’s books to feature black characters – not coincidentally, in the midst of a critical time in the civil rights movement.

Renewed respect for children’s book illustrations started appearing in the early 1980s, led by Japanese museums that displayed the pieces on par with raku pottery, traditional calligraphy and other undisputedly important art forms. The past decade has seen a burst of U.S. museum displays and the growth of facilities to preserve and show it, including the Carle’s establishment in Amherst.

Many say the art will have long-term appeal because it crosses generations, introducing children to art and museums while sparking warm memories for adults.

Simon Keochakian, 72, an art collector and psychologist trained in art therapy, said even with his background in the field, he was unprepared to accept picture book illustrations as serious art before visiting the Carle.

“I thought they were talking about comics, something light and simple,” said Keochakian, keeping an eye on granddaughters Selma and Hannah nearby after a recent story-time gathering at the museum.

“As I learned more about it, I realized it’s an entire genre. I think people are starting to understand that children’s picture book art can be very profound, not just a fun distraction.”

Some mainstream art museums throughout the United States have purchased pieces, but many put on displays with items borrowed from specialty museums such as the Carle or the Mazza Museum of International Art from Picture Books in Findlay, Ohio.

Washington’s Tacoma Art Museum, the Art Institute of Chicago and Connecticut’s New Britain Museum of American Art – one of the first to collect picture book pieces as fine art – all have displayed exhibits.

“I can’t say we’re viewing it quite the way we’re viewing Monets, but I do think there’s been more attention and focus on this,” said Jean Sousa, the Art Institute of Chicago’s director of interpretive exhibits and family programs. “It’s a distinct entity. It doesn’t have to compete with the Monets of the world because it has its own special value as art.”

The appeal of some images has lasted over the decades, such as H.A. Rey’s “Curious George” and Beatrix Potter’s “Peter Rabbit.”

But art historians and educators say only time will tell which of today’s illustrations become tomorrow’s icons. From Caillou to Captain Underpants to Lilly’s Purple Plastic Purse, the staying power has yet to be seen.

“I think some of it depends on how much they’re picked up in different media and how much they’re collected over the years,” said Rutgers University professor emeritus Kay Vandergrift, who taught courses on the subject.

“There are some that are likely to be around forever, but we just can’t predict yet which ones they’ll be,” she said.