''Six Thousand Years of Bread: Its Holy and Unholy History'' is a landmark book by German-American journalist and author Heinrich Eduard Jacob (H. E. Jacob), originally published in 1944. Based on more than two decades of exhaustive research, the book is a sprawling, comprehensive cultural history that explores how bread, agriculture, and grain have shaped human politics, religion, technology, and warfare across millennia. It remains a cult favorite among bakers, food historians, and chefs.

The book is divided into six thematic sections that track the chronological evolution of human civilization through the lens of grain:
1) The Bread of Prehistoric Man -- Explores the primitive relationship with wild grains and the invention of the plow.
2) Bread in the Ancient World -- Examines the sophisticated baking techniques of ancient Egypt, Greece's worship of the goddess Demeter, and the Roman Empire's dependency on grain supplies.
3) Bread in the Middle Ages -- Dives into the dark side of bread history, including the systemic distrust of millers and the devastating outbreaks of ergot poisoning (Saint Anthony's Fire) caused by tainted rye.
4) Bread in the Early Americas -- Highlights how the introduction of maize and the vast landscapes of the New World shifted global agrarian power dynamics.
5) Bread in the Nineteenth Century -- Documents the mechanization of agriculture, the depletion of soil nutrients, and how logistical bread shortages fundamentally crippled Napoleon's army.
6) Bread in Our Time -- Looks at the industrialization of grain in the early 20th century, the weaponization of hunger in World War I, and the geopolitical battle for nutrition.

What makes the book incredibly poignant is H. E. Jacob's own life. As a German-Jew, Jacob was arrested by the Nazi regime in 1938 and interned at both the Dachau and Buchenwald concentration camps. He was eventually released through the tireless efforts of his future wife, Dora, and fled to the United States, where he completed the book. In the final chapters, Jacob recounts his time in the concentration camps, providing a chilling look at the ultimate "unholy history" of bread—surviving on meager rations of bread expanded with industrial sawdust.