Whenever cultures meet, exchange is inevitable. There will be exchanges of goods, of languages, of cultures, and of disease. The epidemics and pandemics sparked by European expansion in the fifteenth and sixteenth centuries were devastating but ultimately encouraged scholars to think critically about disease and its origins. By examining the language and ideas of first-hand accounts of plague, scurvy, syphilis, and smallpox, the evolution of European theories of disease can be traced from the Justinian Plague of 560 AD to the London Plague of 1625 AD. Examining the impact that the European voyages of discovery had on theories of disease shows that expansionism served to catalyze the development of our modern germ theory. [ABSTRACT FROM AUTHOR]