Dante and the Water Cycle in the Commedia: God, Physics, and Flowing Waters

Although in recent years many scholarly works have appeared on the topic of Dante and medieval science, the issue of how he approached the problem of the nature of water and its movements has yet to receive the attention it deserves, in spite of the general consensus on considering the Questio de aqua et terra as Dante's original work.¹ While this late work focuses on a narrower discussion on the place of water, the Commedia displays important references to the paradigms of water evaporation, rain formation, and river flow, which if read systematically provide considerable evidence for suggesting that Dante incorporates a coherent vision of the mechanisms regulating earthly hydrology. Not only does Dante's Commedia sustain significant attention to the mechanics of river flow variation but, as I will demonstrate, the poet also engages with the complex problems at stake in the conceptualization of water's nature and movements. From this perspective, water evaporation, rain formation, river flow and origin, as well as the nature of fresh and salt waters, emerge as parts of a composite problem encompassing different disciplines and dealing with what we now call "the water cycle." In the context of medieval scientific discourses, the question of water movement represents a complex puzzle whose solution involves serious logical challenges related to the relationship between Water and the other elements, particularly Earth and Air, as well as the dispute over their respective natural places. As we will see, Dante's vision of the place of water also implies the distinction between natural water, which is characterized by its physical properties, and spiritual water, which is defined by the cultural values ascribed to it by Christian liturgy and tradition.

Questions about the properties and movement of water have intrigued both natural philosophers and Christian thinkers, who came to articulate the complex mechanisms of water movements by distinguishing between bodies of water while also trying to account for their interconnections.² In Greco-Roman natural philosophy as well as in derivative works within Christian traditions, rivers become the preferred object through which to explore questions about the nature and movement of water.³ In medieval works, such a consideration of rivers as a privileged site for investigating the multifaceted problem of earthly water results from both textual tradition and logical approaches to the assessment of empirical evidence. While springs and seas were (and still are) conceptualized, in fact, as bodies of water whose volumes remain stable, the flow of rivers noticeably changes in relation to rainfall.

Before the development of modern atmospheric and hydrologic science, Aristotle's Meteorologica was the pivotal text for addressing the question of water movements across the atmosphere and land, which involved competencies from different fields of knowledge, noticeably physics and geography, as well as a considerable understanding of the theory of simple and composite elements. As Patrick Boyde notes, in fact, meteorology in the context of ancient and medieval disciplines is an area of knowledge that "takes in all the transient phenomena which involve the transformation of the 'simple bodies' one into another," thus occupying "an essential place between the study of the four elements as such and of compounds."⁴ The difficulty of analyzing the phenomena discussed within meteorology derives not only from the complexity of element theory, but also from the intricate textual transmission of Aristotle's Meteorologica, which contributed to the confusion around specific terminology as well as on the exact mechanics of the many phenomena which are addressed in the work, such as earthquakes, wind, and matters of astronomy.⁵

Medieval and modern commentators have long identified a connection between Aristotle's Meteorologica and the Commedia, particularly in relation to problematic aspects posed by Dante's use of the dry exhalation theory as a model for explaining wind, rainbows, and earthquakes.⁶ Scholars who compare the two works observe how all the phenomena described in Aristotle's text are at some point recalled in Dante's poem, thus speculating that such a parallel might have been the poet's conscious design.⁷ Passages that deal with water...