„Happiness is an imaginary condition, formerly attributed by the living to the dead, now usually attributed by adults to children, and by children to adults.“

„Is adult entertainment killing our children? Or is killing our children entertaining adults?“

—  Marilyn Manson American rock musician and actor 1969

As quoted in MarilynManson.com (2000).
2000s

„The value of marriage is not that adults produce children, but that children produce adults.“

—  Peter de Vries American editor and novelist 1910 - 1993

„Children in school are not students, they are pupils. It is typical of certain kinds of politicians that they should regard children as adults, the better subsequently, and consequently, to regard adults as children.“

—  Theodore Dalrymple English doctor and writer 1949

Mr Brown's self-esteem issue - or, asks Theodore Dalrymple, does Gordon Brown really believe that he can solve the problems of the world? http://www.socialaffairsunit.org.uk/blog/archives/001326.php (January 24, 2007).
The Social Affairs Unit (2006 - 2008)

„Adults are just obsolete children and the hell with them.“

—  Dr. Seuss American children's writer and illustrator, co-founder of Beginner Books 1904 - 1991

On writing for adults, as quoted in Of Sneetches and Whos and the Good Dr. Seuss: Essays on the Writings and Life of Theodor Geisel (1997) by Thomas Fensch, p. 96

„Children are the vessels into which adults pour their poison.“

—  Salman Rushdie, livro Midnight's Children

Fonte: Midnight's Children (1981)

„The difference between children and adults is that they're shorter - not dumber.“

—  Mo Willems American children's illustrator and writer 1968

„Adults should strive to be more like children.“

—  Lorin Morgan-Richards American poet, cartoonist, and children's writer 1975

Speaking at Women's march in Los Angeles (21 January 2017).

„But some children have clearer vision than adults.“

—  Edmund Cooper British writer 1926 - 1982

Prisonner of Fire (1974)

„In their sympathies, children feel nearer animals than adults.“

—  Jessamyn West American author 1902 - 1984

The Life I Really Lived, part 1 (1979)
Contexto: In their sympathies, children feel nearer animals than adults. They frolic with animals, caress them, share with them feelings neither has words for. Have they ever stroked any adult with the love they bestow on a cat? Hugged any grownup with the ecstasy they feel when clasping a puppy?

„I've found what makes children happy doesn't always prepare them to be courageous, engaged adults.“

—  Brené Brown US writer and professor 1965

Fonte: Daring Greatly: How the Courage to Be Vulnerable Transforms the Way We Live, Love, Parent, and Lead

„Women will risk their lives to protect children, but rarely risk their lives to protect an adult man.“

—  Warren Farrell, livro The Myth of Male Power

Fonte: The Myth of Male Power (1993), Part II: The Glass Cellars of the disposable sex, p. 230.

„It can be said that deeply traumatized children grow into adults who live in the minefield of their own extreme emotions. Plus ca change.“

—  Antonella Gambotto-Burke, livro The Pure Weight of the Heart

Fonte: The Pure Weight of the Heart (1998), P. 326.

„For children love is a feeling; for adults, it is a decision. Children wait to learn if their love is true by seeing how long it lasts; adults make their love true by never wavering from their commitment.“

—  Orson Scott Card, livro Pathfinder

Fonte: Pathfinder

„We're a nation of exhausted and over-stressed adults raising over-scheduled children.“

—  Brené Brown US writer and professor 1965

„Children like to work, and are always eager to imitate the work of adults.“

—  Georgi Plekhanov Russian revolutionary 1856 - 1918

Utopian Socialism in the Nineteenth Century, 1913, Ch. 5.

„It is not size or age or childishness that separates children from adults. It is "responsibility."“

—  Jules Feiffer American cartoonist, screenwriter and playwright 1929

The Great Comic Book Heroes http://books.google.com/books?id=zxbuAAAAMAAJ&q=%22It+is+not+size+or+age+or+childishness+that+separates+children+from+adults+It+is+responsibility%22&pg=PA75#v=onepage (1965)

„Children are not afraid to pose basic questions that may embarrass us, as adults, to ask.“

—  Roger Penrose, livro The Emperor's New Mind

Fonte: The Emperor's New Mind (1989), Ch. 10, Where Lies the Physics of the Mind?, p. 448–9 (p. 580 in 1999 edition).
Contexto: Beneath all this technicality is the feeling that it is indeed "obvious" that the conscious mind cannot work like a computer, even though much of what is involved in mental activity might do so.
This is the kind of obviousness that a child can see—though the child may, later in life, become browbeaten into believing that the obvious problems are "non-problems", to be argued into nonexistence by careful reasoning and clever choices of definition. Children sometimes see things clearly that are obscured in later life. We often forget the wonder that we felt as children when the cares of the "real world" have begun to settle on our shoulders. Children are not afraid to pose basic questions that may embarrass us, as adults, to ask. What happens to each of our streams of consciousness after we die; where was it before we were born; might we become, or have been, someone else; why do we perceive at all; why are we here; why is there a universe here at all in which we can actually be? These are puzzles that tend to come with the awakenings of awareness in any one of us — and, no doubt, with the awakening of self-awareness, within whichever creature or other entity it first came.

„There are children born to be children, and others who must mark time till they can take their natural places as adults.“

—  Mignon McLaughlin American journalist 1913 - 1983

The Complete Neurotic's Notebook (1981), Unclassified

„Children are not less intelligent than adults; what they are is less informed.“

—  Philip Pullman English author 1946