Kimmerer shares a memory of being in kindergarten and seeing a snowflake through a magnifying lens. It was the first time she understood that there is more to the world than what people ordinarily see. She compares this moment to her early days of learning to look closely at mosses. Like snowflakes, mosses are made up of tiny, perfectly ordered parts. She admires their complexity and beauty. She notes that one purpose in writing Gathering Moss is to invite readers into the same intimacy with the landscape that she herself has discovered through studying mosses.

It has been three decades since she began studying mosses, and her habit is to wear her hand lens on a cord around her neck. It often becomes intertwined with the cord of the medicine bag she wears as a part of her Potawatomi cultural heritage. Kimmerer sees this as symbolic of the intertwining Western and Indigenous scientific perspectives that she uses in her work. For some time, she felt that her Indigenous knowledge was pushed into the background by her academic education; another purpose in writing Gathering Moss is to foreground that Indigenous perspective again.

A final purpose in writing the book is to share the stories of mosses, because she believes that they have valuable lessons to teach.