Humboldt’s contributions to ecological thinking marked a pivotal shift in how nature was perceived and studied. Prior to Humboldt, the study of nature was often fragmented; scientists would typically examine isolated phenomena without considering broader interconnections. Humboldt challenged this approach, advocating for a holistic view of the natural world which emphasized the interconnectedness of all living and non-living elements. Through this theme, Wulf explores how Humboldt’s revolutionary perspective laid the groundwork for modern ecological science.

Wulf narrates Humboldt’s journey through diverse ecosystems—from the steppes of Russia to the jungles of the Amazon—which provided him with a vast array of empirical evidence that supported his holistic view of nature. He observed how changes in one part of an ecosystem could affect many others, a principle evident in his detailed descriptions of plant geography and climate. For example, in Cosmos, Humboldt describes the distribution of plant species across different climatic zones and elevations. He notes how vegetation patterns are not only influenced by climatic conditions but also affect those very conditions, creating a dynamic, interdependent system. Wulf suggests that these vast ideas are so ingrained in modern ecological thinking that their source is forgotten.