“Michael Gruenbaum, Holocaust Survivor, Dies at 92” read the headline, following Michael’s recent death on March 8. It was difficult for me to believe this could be true—Michael had seemed indestructible. Which, I suppose, is because his spirit is just that.

When I agreed to edit Somewhere There Is Still a Sun, a memoir by Michael co-written with Todd Hasak-Lowy, I was ambivalent. I had taken a class in college on literature of the Holocaust; I remembered how unprepared I’d been for the emotional toll of being steeped in reading about the Shoah day after day. But from the moment I first met Michael, I understood why this book would be different.

It’s not that Michael’s story of his time in the Terezin concentration camp isn’t filled with horror and loss. What narrative from that time isn’t? But Michael’s focus was about making sure that the truth about the evils done to his family and millions of others was portrayed alongside the anecdotes about where and how he’d found hope and—even, at times—joy. He wanted readers to recognize the danger of letting hatred and bigotry flourish, and also to recognize the power of light and love.

In this vein, Michael and Todd and I made a decision to craft the memoir in the immediacy of what Michael’s perspective and experience had been at the time, without the context of hindsight. This meant that the word “Holocaust” never appeared on the pages—because that name didn’t exist while Michael was living it. It meant that when one reads his story, Michael allows us to experience not only the fear and the sadness he felt, but the innocent bursts of pleasure he had being a young boy playing soccer with friends in the midst of a horrific backdrop. The cracks of light that found their way through.

Everyone who knew Michael knew that the credo he lived by was never to take “no” for an answer. After becoming a published author in his 80s, Michael truly never rested from dedicating himself to amplifying the book’s reach. Time and again he’d ask for something that his agent and I would gently explain was impossible or at least unlikely, and he’d smile and say he was going to try anyway. And time and again, he made it happen. Michael asked for lists of each foreign publisher large and small in every country and wrote thousands of personal letters to them, ultimately laying foundations for a staggering 19 translations. (He recently told me that a 20th was in the works—I have no doubt it will come through.) Michael pitched himself for ongoing publicity well past the initial window of his memoir’s publication, after which point coverage is difficult to obtain, and regularly secured features in a wide range of outlets. He was constantly emailing us photos of him standing beside some famous public official, holding a copy of his book. Michael’s wide grin in these photos could brighten even the toughest day.

But it wasn’t simply Michael’s determination to share his story that most impressed me; it was the reason for that determination. Michael carried close the knowledge that he spoke for the many who couldn’t. He needed this book to memorialize his love both for the people who did not survive, and for the people responsible for his survival. Somewhere There Is Still a Sun is a testament to how Michael’s mother—after losing her husband to a kind of horrific death that would break anyone—stitched teddy bears for Nazis to keep her children alive. It’s a testament to Michael’s aunt Louise, who told Michael’s mother before she left on a transport “east” (this is how transport to Auschwitz was described to those imprisoned at Terezin) that if she could, she would send a postcard when she arrived, containing a coded message. Louise explained that Michael’s mother should ignore the words themselves and only pay attention to if those words were slanted up or down. Down meant things at Auschwitz were bad, worse than at Terezin. This postcard made its way to Michael’s mother, who recognized that the otherwise innocuous words revealing nothing of concern were slanted down, and so she had to fight with all she had to keep her kids from that transport “east.” (A photograph of that postcard, among other artifacts, is included in the book—it’s awe-inspiring to actually be able to see images of documents that saved lives.)

The book is a testament, too, to Michael’s love for the boys with whom he was imprisoned at Terezin. They called themselves the Nesarim, Hebrew for eagles. Michael was one of only 12 of the Nesarim who made it out. He shared images with us of notes these boys had given him during their time together, and one morning in my office, a colleague and I chose a note at random to run through an online translator. We saw that it simply said, “Remember me.” I don’t think I’ve ever felt the breathless enormity of what this job can be more than I did in that moment, when those words flashed across my screen. I kept telling Michael, over and over: “That’s what you have done with this book. You are remembering him.”

The title of the book comes from a letter Michael’s mother wrote after the war. She was battling the overpowering sadness of all that had been lost, but maintained that they must remember that in all of this darkness, somewhere in the world there was still a sun (son…). Isn’t that something—that she could still believe that? And that Michael could do all he did to carry on the legacy of her belief? He was, in fact, speaking to an audience of kids about his book the day before his death. I hope that if you’ve read these words about Michael and his memoir, you will take a moment to look up the book and read his story, to help me do what meant the most to Michael, now that he is sadly no longer here with us—to keep the story of the Nesarim alive.

Abrams is v-p and editor-in-chief of the Labyrinth Road imprint at Random House Children’s Books.