Why did Johanna Spyri write the book Heidi?

There are multiple accounts as to the reason why Johanna Spyri wrote the book Heidi. One version suggests that Spyri was inspired to write the story by her own childhood memories of spending summers in the Swiss mountains. She was particularly fond of the village of Maienfeld, which is where she set the story of Heidi. Another version claims that Spyri wrote Heidi as a response to the increasingly industrialized society of her time. She wanted to create a story that would show the beauty and simplicity of rural life and to remind people of the importance of nature and fresh air. Additionally, Spyri may have been inspired by the plight of the poor children who were often exploited as cheap labor in the factories and mills of the cities. Heidi's story may have been intended as a way to raise awareness of this issue and to encourage readers to help these children.