introducing the concept of bioluminescence and tracing its recognition throughout history, highlighting early theories that attempted to explain its occurrence in various organisms. Harvey discusses ancient observations of luminous animals by notable figures such as Aristotle and Robert Boyle, detailing the understanding of luminous phenomena, such as the glow of certain fungi and the phosphorescence of marine organisms. The author emphasizes the diverse distribution of luminous species across various biological groups, establishing that while some light production is secondary (due to bacterial infection), many organisms generate light intrinsically. This groundwork prepares readers for a deeper examination of the complex interplay between biology, physics, and chemistry in the subsequent chapters. (This is an automatically generated summary.)