"Collapse" is an exploration of why certain societies throughout history have thrived while others have deteriorated and collapsed. The book delves into environmental problems, climate change, rapid population growth, and unwise political decisions as factors that contribute to the downfall of a civilization. The author uses examples from history such as the Mayans, the Vikings in Greenland, and modern examples like Rwanda and Haiti, to illustrate his points. It serves as both a historical analysis and a warning for modern societies to learn from the past in order to avoid a similar fate.

"Plagues and People" is a pioneering work that examines the complex relationship between human societies and infectious diseases over the centuries. The book explores how waves of epidemics have influenced health, social, and political outcomes across different civilizations, shaping the course of human history. By analyzing the impact of widespread diseases from ancient times through the modern era, it highlights the role of infectious outbreaks in precipitating demographic shifts, altering societal structures, and influencing the rise and fall of empires. The narrative underscores the interplay between disease and human progress, revealing how humanity's efforts to control and mitigate the effects of plagues have driven advancements in medicine and public health.