In this book, which originated from a lecture given at Harvard University in 1933, Lovejoy examines the emergence, development, and dissolution of a philosophical, more specifically, a cosmological thought that has significantly influenced Western thinking for more than two millennia. The book is a major cultural-historical investigation into the overall cultural impact of an originally cosmological-metaphysical idea. The impressive and simultaneously cautious manner in which Lovejoy relates astronomy, biology, art history, landscape gardening, philosophy, literary history, and theology to one another and ties them to a common denominator—namely, a specific speculative understanding of being—also makes it one of the most significant achievements of interdisciplinary research.