Watch Julian Lennon on New Children's Book, John Lennon's 'Odd' Wisdom

"[John] mentioned once [that] should he ever pass, a way he would let me know that he was OK ... would be in the form of a white feather," singer said

In a new interview, Julian Lennon discussed his environmentally conscious children's book and John's "odd" words of comfort.

Julian Lennon addresses the critical urgency of pollution in his new children's book, Touch the Earth, out this week. The story focuses on a group of kids flying the globe on a plane named the White Feather Flier – a name inspired by Lennon's dad, John – to learn about the planet's desperate need for filtration, irrigation and ocean life protection, The Associated Press reports.

"We've failed miserably in looking after our environment. I think this is a great way to approach children into realizing what's at stake, and to help educate and help them make decisions about the right things to do for the future," Lennon told the AP. "It's for those with inquiring minds who are asking, 'Why'?"

Touch the Earth, co-written by Bart Davis and illustrated by Smiljana Coh, is the first of three children's books Lennon is planning in conjunction with White Feather Foundation, the songwriter's environmental and humanitarian organization.

Lennon told the AP that the foundation's name was inspired by a "very odd" remark from his dad, John Lennon, during one of the rare occasion when they saw each other. "He mentioned once [that] should he ever pass, a way he would let me know that he was OK, or that we were all going to be OK, would be in the form of a white feather," he said.

The singer said he learned of the White Feather story by an Aboriginal tribal elder from the Mirning tribe during a tour behind his fifth LP, 1998's Photograph Smile. "[It] definitely took my breath away," he wrote, adding, "The White Feather has always represented peace to me, as well as communication."

"It was a freaky moment, but one I took to heart immediately," Lennon told the AP. "I realized that this was about stepping up to the plate now and, you know, I can sing all I want about this stuff but am I actually going to do something about it? So I spent 10 years making a documentary [2006's Whaledreamers] about the Mirning people."

After that life-altering moment, the singer launched his foundation, which has worked with clean water initiatives and health clinics in countries like Kenya and Ethiopia. A portion of proceeds from Touch the Earth will benefit the foundation.

Lennon added that his humanitarian work is carried out to honor his mother (and John Lennon's first wife), Cynthia, who died in 2015. "That was all based around wanting to make her proud," he said. "I try to continue all the work that I do in her name."