Over the years, Ms. Mathers had donated much of her original artwork, including all the work for the Lottie books, to the Eric Carle Museum of Picture Book Art in Amherst, Mass. It was a natural fit, said Nichols B. Clark, the museum’s founding director and chief curator emeritus. “They both used humble animals to tell very big stories,” he said of Mr. Carle, the author of “The Very Hungry Caterpillar,” and Ms. Mathers.
Mr. Clark received one of Ms. Mathers’s goodbye letters. She wrote that she and her husband had “become frail, physically very little, mentally not so little.” She noted that by the time Mr. Clark would receive his letter, the couple would be in their shared grave in Oysterville, Wash. “You can hear the ocean and the cows often come to graze early evening,” she wrote.”
She wrote of the pleasure she took in being part of the Carle Museum, and she included an unpublished manuscript and a generous check.
Ms. Mathers is survived by her son, Tillman Richter; a grandson; and her brother, Gero Gerweck. Her marriages to Eberhard Richter and David Spence ended in divorce.
“Petra was really very important and not as celebrated as she deserved to be,” Anne Schwartz, Ms. Mathers’s longtime editor, said by phone. “Each book is a slice of life beautifully captured, a little gem. She was a keen observer of the minutiae of the world around her, the small dilemmas of life. And she was a romantic to her very bones.”
“Sophie and Lou” (1991), one of Ms. Mathers’s early titles, was the story of a mouse who overcomes her painful shyness and learns to dance, with the help of an equally bashful suitor. The dedication, which Ms. Mathers wrote in ink and adorned with winged hearts, reads, “To Love, and those who dare put all their eggs in one basket.”
