Man or Matter by Ernst Lehrs explores the relationship between human consciousness, the physical world, and the nature of matter from a spiritual and philosophical perspective. Drawing upon Rudolf Steiner's spiritual-scientific approach, Lehrs examines how modern scientific thinking can be expanded through a deeper consideration of human perception, consciousness, and the forces underlying the material world.

The book seeks to bridge scientific inquiry and spiritual understanding, discussing subjects such as perception, matter, space, light, and the human experience of nature. It offers readers an introduction to Anthroposophical approaches to science and provides a distinctive perspective on the relationship between the material and spiritual dimensions of existence.