We could, however, define it in a way that would put true adulthood decades away from legal majority for most people. Adulthood is when you start realizing that the classics foisted upon you in school are classics for a reason -- namely, that they're actually amazing.
In high school I read Great Expectations and A Tale of Two Cities. A few years ago I decided that I ought to give David Copperfield a try, seeing as it tops lists of the greatest novels in English. And I discovered, much to my shock, that I adored it. That I adore Dickens, and would happily spend the rest of my days reading through the entire Dickens catalog. Nothing would have shocked that 16-year-old slogging through Great Expectations more.
Thanks to the A.V. Club's Wrapped Up In Books monthly feature, I just finished Philip K. Dick's A Scanner Darkly. "You know what's a really good book?" I told Noel after turning the last page on my Kindle. "A Scanner Darkly." It shouldn't be surprising that books widely acclaimed, books that have taken their place in canons of one kind or another, are actually wonderful to read -- affecting, surprising, deeply emotional, beautifully written. But there's the child in me that hates to be told and is tired of hearing the unanimous voice of her culture.
It's liberating to be an adult and to strike out into the heart of artistic halls of fame, able to fathom the radical notion that quality might be present and that I might be able to appreciate it. This is a marker of adulthood that I didn't pass until just a few years ago -- most probably later than I should have, if I weren't so stubborn or blind. At least I have years of classics ahead of me to explore, like the well-trodden paths I never bothered with because so many had been there before me.