Girolamo Fracastoro's De Contagione et Contagiosis Morbis proposed that epidemic diseases were spread by transferable seeds (seminaria morbi), laying theoretical groundwork for germ theory centuries before its confirmation.

Fracastoro's proposal of germ theory in 1546 introduced the concept of invisible agents causing disease, which permeated the metaphorical language of poetry. This idea resonated with moral and political verse, inspiring poets to explore themes of hidden corruption and societal decay.