Tom Lichtenheld was a star art director at a Chicago ad agency, doing children’s books as a side gig, when his creative director mentioned knowing someone from a stint at another ad agency who wrote children’s books, too and offered to make introductions. Lichtenheld and Amy Krouse Rosenthal were instantly simpatico: 10 books, several awards, and a full-time book writing career for Lichtenheld followed. “Little did [the creative director] know that he was setting me up to quit my job,” Lichtenheld said with a laugh. The duo’s final book, Moo-Moo, I Love You! was finished by Lichtenheld after Rosenthal died of ovarian cancer in 2017; it arrives this month. “Amy and I had a wonderful collaborative relationship,” he said.

Can you tell us about that first meeting?

We met in Millennium Park. It was a hot summer day, we took off our shoes, and had our feet in the fountain. Amy said, “I have an idea for a book.” She got out her pen, drew “OK” on the palm of her hand, and said, “When you turn it sideways it looks like a stick figure, a person. I think there’s a book idea in that.” And I said, “I’d like to work on that book with you.” [The OK Book was published in 2007.]

We got contracts for a couple more books, and with Amy’s prompting I [eventually] left my advertising job and we continued to work together. I was not real secure about quitting my job [at first]. I was used to a regular paycheck my whole career, and publishing is never a sure thing—I tell people I never know how much I’m going to make and I only get paid twice a year.

What was the collaborative process with Amy like?

It was never traditional. She never sent me a manuscript and said, “Illustrate this book.” We both had worked in advertising, and in that business, two people sit in a room and come up with ideas together. You can’t take it personally, you’re just riffing, you have to be fast, and ultimately, there’s no sense of who drew what and who wrote what—you’re in it 50-50.

We’d get together every six or nine months, maybe meeting in a coffee shop, and throw all our scraps on the table—half-baked ideas or half-baked notions. I’d see something and she’d expand on it or vice versa.

It really felt good when I had a good idea that was only 75% there, and I’d show it to Amy, or the other way around. She’d been working on Exclamation Mark (2013) for a while, and she couldn’t get past the pivotal turning point in the book, and I said, “What if we did this?” I was working on I Wish You More (2015) and while I’d sold it to a publisher, they said it’s not fully baked yet. I asked Amy to help me, and between the publisher and Amy they figured out what to do with it.

We didn’t always agree. Our tastes were probably different in some ways. She was great at telling me when she didn’t think my drawings were good enough. She made one tiny little comment about the detail in a girl’s foot, and I realized the whole drawing stunk and I had to do it over again.

How did Moo Moo take shape?

Amy called me one day and said she had an idea based on moo puns. I was in New York when she called me, and I’d had a terrible day. She said, “I want to do this book that’s just a bunch of moo puns, and I said, “That’s a terrible idea and I love it.” I started working on it right at LaGuardia, and it just lifted my spirits. She wanted to do it as a novelty book, a gesture from one adult to another. That became Holy Cow, I Sure Do Love You (2017).

Abrams had always said there’s a children’s book in Holy Cow. But we kept putting it aside and then Amy got sick. She passed away in 2017, and a year later the publisher asked if I would finish the children’s version [which became Moo-Moo]. Amy’s husband Jason was all for it. I said let me try it and see how it feels and it felt good—it felt like I was reconnected to her. And I know it’s something she would have wanted and appreciated.

The beginning is hers: “I love you no matter your moo-d. Good moo-d…Bad moo-d…Worried moo-d…Shy moo-d…Sad moo-d…Silly moo-d.” I had worked with her enough that I could channel her voice and write the rest of it—although it’s tough to come up with enough content based on one phonetic sound. You come up with the first eight really fast. Then I got to the part where I had to take a walk and let the words come to me instead of trying so hard.

Your books together deal with some big topics like emotional resilience, being brave, and self-esteem. They’re ideas that have tripped up many picture book authors—how did you find a way to handle them without being sentimental or preachy?

Kids don’t like preachy books. They can sniff them out a mile away. You have to come at them through a story rather than a message. It’s like a parable: good parables are good stories first and foremost. Sometimes, people tell you what the message is. There are times when I’ll release a book and a teacher will tell me, “That’s a good book for identifying emotions.” Well, I had no idea I was creating a book about identifying emotions.

Amy got there the same way through story or through a device. She saw an ATM machine and made stickers that read, Always Trust Magic. Like any artist, Amy saw ordinary things apart from their prescribed context then shared them in a new context, making them extraordinary. She paid attention to things most of us ignore, and she was always paying attention. In a 2013 tweet, Amy turned this trait into advice about how to live—or change—your life. “Pay attention to what you pay attention to. That’s pretty much all the information you need.” Amy was profoundly aware that, while we may not have much control over the amount of time we get to spend experiencing the world and the people around us, we do have control over how meaningful that time will be.

Moo-Moo, I Love You! by Amy Krouse Rosenthal and Tom Lichtenheld, illus. by Tom Lichtenheld. Abrams, $17.99, Sept. 22 ISBN 978-1-4197-4706-9