Einstein himself praised this fascinating work on numbers, which was first published in 1930, then revised and expanded through the 1954 4th ed. reprinted here with a foreword by Barry Mazur (Harvard U.) and a brief preface by his brother Joseph Mazur (Marlboro College). The story is written for the general reader and conveys in simple, clear language, with many examples and quotes, the great and profound meaning that lies behind the human invention of numbers and math by showing their relation to human knowledge and experience of all kinds. New endnotes and an annotated bibliography have been added