The cycles of birth and decay in the physical world are the subject of this scientific inquiry, which explains how elements transform into one another. Aristotle debates the concepts of mixture and growth, refuting earlier atomist theories in favor of a continuous material substrate. The text details how the interaction of hot, cold, wet, and dry qualities drives the perpetual motion of the sublunary sphere. It is a foundational text for understanding the ancient view of chemistry and the conservation of matter.