This book is a primer on the philosophy of stoicism, resurrected from its origins in Greek and Roman philosophy. The original philosophy was based on a reasoning process which it was assumed would lead to a virtuous life. Zeno, the founder of stoicism, did not begin expounding on its teachings until he was in his forties. He believed that the purpose of life was "to live consistently." Cleanthes, his disciple, added "with nature," so that the purpose of life became "to live consistently with nature."