Matthew McConaughey Says His First Children’s Book 'Just Because' Came to Him as a 'Ditty in a Dream'

"It was a song in my mind, and I got up and wrote it down," the actor tells PEOPLE

For Matthew McConaughey, inspiration for his debut children’s book hit in the middle of the night. In a dream. In song.

"It came to me at 2:30 a.m. as a ditty in a dream," the actor, 53, tells PEOPLE of what would become Just Because, out Sept. 12.

"It was a song in my mind, and I got up and wrote it down."

A spirited collection of life lessons and conundrums untangled in rhythmic couplets, the picture book sparked "a lot of good conversations" with his kids Levi, 15, Vida, 13, and Livingston, 10, wife Camila, and even his ever-discerning mother Kay, he says.

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Related: Matthew McConaughey Announces His First Children's Book, 'Just Because' : 'Speaks to the Kid in All'

"My mom’s 91 and she said, 'That’s not just for kids. You even reminded me of some things in there.'"

The Oscar winner, whose 2020 memoir Greenlights became a bestseller, says he hadn't consciously set out to write a children's book.

"Just being a dad, I mean, you’re thinking about your kids all the time [and] I think that afternoon, I’d been having conversations with my children about certain new things that they were crossing for the first time or, 'Well, this happened and I’m not sure how to feel about it. And I wanted to do this, but I felt I needed to do this, and I was confused,' " he says.

"Evidently it was in my subconscious… Once I knocked all the couplets down in the rhythm, it sort of wrote itself."

McConaughey valued feedback from his kids about all aspects of the book.

"They liked it. Vida is very visual, so she loved the pictures that [illustrator] Renée [Kurilla] did," he says. "I ran it by my kids. We went through scenarios [explored] in it."

One of the couplets that resonated, he says, was "Just because you’re wailing, doesn't mean you're a crier. Just because you lied, doesn’t mean you’re a liar."

Related: Matthew McConaughey on His Memoir Writing Process: 52 Days Alone in the Desert (Without Electricity!)

"We talked about that one quite a bit because my kids have seen it," McConaughey says. "We do it all the time: We label somebody. Somebody fibs to you: 'Oh, you’re a liar.' Well, that's a big blanket to put on somebody. If you call someone a liar, they get defensive: 'Whoa, my whole being? You mean I'm all about untruths?' But if you say, 'No, that was a lie,' that person has the choice now to go, 'I know, I'm sorry about that.'"

Ultimately, he hopes Just Because is a relatable conversation-starter for families and "speaks to the kid in all of us."

For more from McConaughey, pick up this week’s issue of PEOPLE, on stands Friday.

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Read the original article on People.