Why did Louis Agassiz reject Charles Darwin's theory of evolution?

Louis Agassiz rejected Charles Darwin’s theory of evolution because his own scientific worldview was rooted in the doctrine of special creation and catastrophism.

While Agassiz acknowledged the progressive development seen in the fossil record, he maintained that new species could not arise from environmental changes or hereditary modifications. Instead, he believed that each species was an independent "thought of God" and that homologies were merely "associations of ideas in the Divine Mind." Influenced by Plato, Agassiz viewed the natural world as a series of repeated, divine interventions rather than a process driven by physical interactions between populations and their environments. Consequently, he could not accept the conceptual framework of natural selection, as it contradicted his belief in the lack of hereditary continuity between distinct types of organisms.1