Humans have determinedly sought answers to why we are here and how we should live. The study of the history of ideas is of central importance for understanding how we have become who we are. O'Donnell presents an excellent overview of the major philosophers and movements from the ancient times to the present day, blending philosophy, religion, ethics and spirituality, and showing how they have influenced society and history. Beginning with the Greeks, the author covers eastern philosophy, the birth of Christianity, the medieval period, the enlightenment, the modern age and the postmodern condition. The book also explores how concepts of God have changed as different world-views have developed. Major thinkers covered include: Socrates, Plato, Aristotle, Augustine, Aquinas, Descartes, Kant, Newton, Nietzsche and Einstein.