How we think about being shapes how we live in the world, from the ground up. This book surveys the shift from the old ontology to a modern view of being, showing how categories and strata organize reality across levels from matter to mind. It invites readers to follow a clear, contemporary account of what it means for things to exist and how we know them. - Learn why philosophy argues that a firm grasp of being is essential for any systematic account of science, ethics, and society. - See how Hartmann describes ontological strata and the rules that govern how categories move between levels. - Discover how the recurrence and emergence of categories help explain novelty, unity, and diversity in the real world. - Grasp the relationship between thought and reality, including how knowledge reflects and partly constructs ontic structure. Ideal for readers curious about the foundations of philosophy, metaphysics, and the science of being, this edition suits students and general readers alike who want a rigorous yet accessible map of Hartmann’s central ideas.