In the book, Jahren often draws parallels between the growth and development of people and plant life, emphasizing that neither follow strictly linear paths. Many of the more important quotes from the book are about these themes.

For example, Hope writes of working in the laboratory as a child with her father, a scientist and professor:

He taught me that there is no shame in breaking something, only in not being able to fix it.

The connections between science and relationships are a big focus for Jahren as well. She writes:

Love and learning are similar in that they can never be wasted.

The book includes multiple other metaphors on this topic. In one of them, Hope compares risk-taking in relationships to a tree taking root. One part of this passage reads:

The tiny rootlet has only one chance to guess what the future years, decades—even centuries—will bring to the path of soil where it sits. It assesses the light and humidity of the moment, refers to its programming, and quite literally takes the plunge.

In other words, trees, like people, only have a limited amount of time to imagine the consequences of a permanent decision before they have to put their roots down and accept whatever comes after.