Mr. Ungerer’s career is also enjoying something of an extended celebration. Phaidon Press recently reissued several of his children’s books with plans to publish more in October, and the Eric Carle Museum of Picture Book Art in Amherst, Mass., just opened a retrospective, “Tomi Ungerer: Chronicler of the Absurd.” A documentary about his life will be released this fall. A prolific author of books for both children and adults, including “The Mellops Go Flying,” “Moon Man” and “The Three Robbers,” Mr. Ungerer has also pursued sculpture, architectural design and advertising over the course of his career.

Born in Strasbourg, France, he moved to New York in 1956, later lived as a pig farmer in Nova Scotia (which he documented in a memoir, “Far Out Isn’t Far Enough,” also recently reissued) and finally settled on the west coast of Ireland. His arrival in New York at 25 brought instant success: In addition to his children’s books, he created advertisements for The New York Times in the ’60s and illustrated for the Op-Ed page, as well as for Esquire, Life and The Village Voice. After the publication of his erotic drawings, in books for grown-ups like “Fornicon” and “Guardian Angels of Hell,” his children’s books went out of print.

Yet it is primarily as a children’s book author that Mr. Ungerer has been visiting the United States this month, where he was celebrated by the French Consulate and by his fellow illustrators, including Jules Feiffer. Despite a sturdy cane that looks as much like a weapon as like a walking stick and complaints of fatigue, Mr. Ungerer was as animated and droll as ever as he sat in a SoHo hotel bar for an interview. Excerpts are below.

Q. You’re here courtesy of Phaidon, as a children’s book author, but you mentioned to Jules Feiffer that children’s literature is really a sideline for you.

A.: In a way, yes. I’ve written some 150 books, for adults and children, both fiction and nonfiction. I do engineering, I design monuments, I design buildings. In Germany I designed a kindergarten in the shape of a cat. The children enter the mouth and go downstairs inside the tail. I’m a bit of bee, but basically I am an author.

Q. You’ve called your books “the nightmare of the pedagogues.” Why is that?

A. In my children’s books, you’ll always find an element of fear. I think children are thrilled with fear, and they have to be taught how to get over it. When I was a child, I was scared of the night and the dark, so my brother took me to the cemetery on a moonlit night. And I got over it. Then I would go out at night in a bed sheet and try to scare other people.

Why am I the pedagogues’ nightmare? They think I traumatize children. They think children should be loved and protected. But if you do only that, they’re not ready for life.

Q. You have also been called the bad boy of children’s literature.

A. I’ve been an instigator. I want children to make fun of adults. As I’ve often said, children know where children come from, but not where adults come from.

Q. Is there an overriding message in your children’s books?

A. Yes, possibly. Every human being has something the others don’t have. That makes him an individual. You should be aware of your differences and exploit them. This is why I often use animals that everyone hates — a snake, a vulture, a bat — in my books. All those animals are redeemed by the fact that they had appendages or qualities the others didn’t have. In the end they become the heroes.

Q. Your books avoid simple words like tree or bird or flower.

A. Yes. I’m in love with language. Between the ages of 3 and 7, children can learn three languages a year. If you’re not teaching them another language, you can always develop their vocabulary. Make them ask, “What does that mean?”

Q. Do you think children’s literature underestimates children?

A. Absolutely. Children are born critical; they’re not stupid. They know what’s going on.

The very fact that they have lists of words for different ages: these are the words a 6-year-old should know. That was what was so wonderful about Ursula Nordstrom [Mr. Ungerer’s celebrated editor at Harper & Row]: she let me use the words I wanted to use. I always go back to Edward Lear and Hilaire Belloc and Lewis Carroll. Nonsense words. Everybody should learn “Jabberwocky.”

Q. In your conversation with Jules Feiffer, you talked about the difference in writing and illustrating children’s books rather than just doing one or the other.

A. Look, it’s a fact that the children’s books that withstand the grinding of time all come from authors who did both. Because the author has a vision, and there’s an osmosis between the oral and the visual, which come together and mix.

Q. Is there a line between children’s literature and grown-up books?

A. That’s a very good question. If I write a book, I do it mostly for myself, for the child in me and for the adult in me. The criterion for my children’s books is: If I were a child, would I like it? That’s very egotistical, but it’s the same thing with my books for adults. I wouldn’t do a book if I didn’t want to partake and share. With a book, I can do both: I give and I share.