Meghan Markle celebrated Father’s Day on Sunday by discussing the deeply personal story behind her new children’s book “The Bench,” which is about a father’s relationship with his child through the eyes of a mother.

In an interview with NPR, Meghan explained that she had been racking her brain trying to think of a first Father’s Day gift for her husband Prince Harry following the birth of their first child Archie. The duchess added that she wanted something “sentimental and a place for him to have as a bit of a home base with our son.”

Meghan ended up deciding to give Harry a bench with a plaque on the back that included a poem that would eventually become the book “The Bench,” which is various vignettes featuring intimate stories between fathers and their sons that focus on spending time together on a bench.

“I often find, and especially in this past year, I think so many of us realized how much happens in the quiet,” Meghan said. “It was definitely moments like that, watching them from out of the window and watching [my husband] just, you know, rock him to sleep or carry him or, you know … those lived experiences, from my observation, are the things that I infused in this poem.”

Meghan then enlisted the help of illustrator Christian Robinson, who she knew would help her show a lighter side of masculinity, which she decided to achieve through the use of watercolor.

“I wanted him to just try something a little bit new and work in watercolor,” Meghan explained. “And that was specifically because I just felt that when you talk about masculinity and you talk about fatherhood, it can often not come across with the same softness that I was really after for this book. And I just wanted this to feel almost ethereal and light and Christian was able to use that medium and create the most beautiful images.”

Meghan also wanted to show the diversity of the myriad of fathers and sons around the world.

“Growing up, I remember so much how it felt to not see yourself represented,” said Meghan, who identifies as being mixed-race. “Any child or any family hopefully can open this book and see themselves in it, whether that means glasses or freckled or a different body shape or a different ethnicity or religion.”

Meghan was determined to include a military father after being inspired by a soldier she met years ago on a USO tour whose deployment kept him form his son.

“He had told me the story about how he wasn’t able to teach his son how to play catch because he was away,” Meghan explained. “And so he and his son would mail this baseball back and forth to each other from Texas to Afghanistan and write the date on it. That stuck with me.”