On the Heavens

Summary

In the book «On the Heavens», Aristotle explores the nature of celestial bodies and their movement. He examines the structure of the universe, asserting that it consists of concentric spheres with Earth at the center. Aristotle divides the world into two parts: the sublunary world, where everything is subject to change and decay, and the superlunary world, which is eternal and unchanging. He describes the movement of celestial bodies as perfect and circular, attributing this to their divine nature. Aristotle also discusses the elements that make up celestial bodies and introduces the concept of aether as a fifth element, distinct from the four earthly elements. The book is a significant work in the history of astronomy and philosophy, having a profound influence on medieval science and cosmology.