In Once More We Saw Stars (Knopf, May), Greene writes about life after the death of his two-year-old daughter, Greta.

This began as a journal. What was the writing like?

I bled it out. My first journal entry was two or three days after the accident and I was just writing down what I felt—very pure and raw. It was a survival mechanism so as not to be blinded by my own grief. I’d scream and cry to my therapist then write down everything I remembered saying. It became visceral, like tending to a wound.

How did your wife’s pregnancy affect your writing?

It became a place of reckoning. How much trauma could I purge and how much could I reckon with before we were tasked with caring for another child? I wrote it on a countdown clock with the idea that we were going to clear a peaceful space for Harrison when he entered our lives. It was unspeakably important to me that our child not be born into a haunted version of the life we gave to Greta or to grow up with a sense that their parents were broken. I loaded every possible metaphysical stake you could pile onto one project. I said, “This is going to be the story of me, my wife, my daughter, and my unborn son.”

What surprised you most while writing this book?

I lived with the words on my own for about a year and half. I had no sense of what I’d written or what it felt like to read. When an excerpt was published in the New York Times, the response was a tidal wave. I spent hours and hours answering people on Twitter who had lost children, had children in the ICU, or had been born after their parents lost a child. It was as if Greta had found a way to me to show me all these people who were suffering the way my wife Stacy and I were suffering. In that way, all the surprises have been beautiful and show people’s capacity for love and empathy.

What do you hope readers will take away?

There’s going to be anguish and despair when a family loses a child, but the book is meant to make you feel good in the end. I hope it helps people find a stronger connection to their love for their children, and I wanted to give people something that left them feeling affirmative and better than when they went in. I don’t think I would have written about my experiences if that wasn’t the story I wanted to tell.