On Generation and Corruption (Book II) – Aristotle – Revised Oxford Translation, edited by Jonathan Barnes

What the Book Explores

In the second book of On Generation and Corruption (De Generatione et Corruptione), Aristotle shifts his focus from the abstract mechanics of change to the specific material constituents of the sublunary world. This work represents a foundational effort to explain how the physical universe is composed and how it undergoes constant transformation. Aristotle explores the nature of the primary elements—Earth, Air, Fire, and Water—proposing that they are not fundamental, indivisible building blocks, but rather manifestations of more basic tactile qualities: Hot, Cold, Dry, and Moist.

The text systematically examines the following themes:

The Four Elements and their Qualities: Aristotle argues that each element is a combination of two primary qualities. Fire is Hot and Dry; Air is Hot and Moist; Water is Cold and Moist; and Earth is Cold and Dry. This classification system provided the structural logic for much of Western natural philosophy for nearly two millennia.
Reciprocal Transformation: A central premise of Book II is that elements can transform into one another through the change of their constituent qualities. For instance, when the Cold in Water is overcome by Heat, it transforms into Air (vapor). This cycle of generation (coming-to-be) and corruption (passing-away) ensures the continuity of the material world.
The Cause of Perpetual Change: Aristotle addresses why change never ceases. He attributes the eternal cycle of generation and corruption to the movement of the celestial bodies, specifically the sun’s path along the ecliptic (the “oblique circle”). The sun’s approach and retreat drive the seasonal cycles of growth and decay on Earth.
The Continuity of Existence: The work concludes with a philosophical reflection on the circularity of time and matter, suggesting that while individual things perish, the species and the elemental cycles remain eternal.

Historical / Cultural Context

Written in the 4th century BCE, On Generation and Corruption serves as a critical bridge between the earlier Presocratic theories of matter and the later systematic sciences of the Middle Ages and the Renaissance. Aristotle was responding to thinkers like Empedocles, who believed the elements were eternal and unchanging, and the Atomists (Leucippus and Democritus), who argued that all change was merely the rearrangement of indivisible particles.

Aristotle’s qualitative approach—viewing the world through sensory properties like heat and moisture—aligned closely with human perception. This made his system highly intuitive and influential. During the medieval period, this text became a cornerstone of Scholasticism and provided the theoretical framework for alchemy. The alchemical pursuit of transmutation was predicated on the Aristotelian idea that the qualities of matter could be manipulated to transform one substance into another.

Furthermore, the text’s connection between celestial movement and terrestrial change deeply influenced historical astrology and medicine (such as the theory of the four humors), linking the microcosm of the human body to the macrocosm of the universe.

Who This Book Is For

This work is of primary interest to those exploring the history of science and the evolution of human understanding regarding the natural world. Readers interested in the symbolic foundations of alchemy, the history of philosophy, or the development of early cosmological models will find Aristotle’s rigorous categorization of the elements illuminating. It is equally valuable for students of classical literature who wish to understand the physical reality as perceived by ancient Greek society. While scholarly in nature, the text offers profound insights into how humans have historically attempted to find order and permanence within a world of constant flux.