The Six Ages of the World is a Christian historical periodization first written about by Saint Augustine circa 400 AD. It is based upon Christian religious events, from the creation of Adam to the events of Revelation. The six ages of history, with each age lasting approximately 1000 years, were widely believed and in use throughout the Middle Ages, and until the Enlightenment, the writing of history was mostly the filling out of all or some part of this outline. The outline accounts for Seven Ages, just as there are seven days of the week, with the Seventh Age being eternal rest after the Final Judgement and End Times, just as the seventh day of the week is reserved for rest. It was normally called the Six Ages of the World because they were the ages of the world, of history, while the Seventh Age was not of this world and lasting forever. Six Ages The Six Ages are best described in the words of Saint Augustine, found in De catechizandis rudibus (On the catechizing of the uninstructed), Chapter 22: The First Age: "The first is from the beginning of the human race, that is, from Adam, who was the first man that was made, down to Noah, who constructed the ark at the time of the flood." The Second Age: "..extends from that period on to Abraham, who was called the father indeed of all nations.." The Third Age: "For the third age extends from Abraham on to David the king." The Fourth Age: "The fourth from David on to that captivity whereby the people of God passed over into Babylonia." The Fifth Age: "The fifth from that transmigration down to the advent of our Lord Jesus Christ." The Sixth Age: "With His [Jesus Christ's] coming the sixth age has entered on its process." Theory Saint Augustine taught that there are six ages of the world in his De catechizandis rudibus (On the Catechising of the Uninstructed). Augustine was not the first to conceive of the Six Ages, which had its roots in the Jewish tradition, but he was the first Christian to write about it, and as his ideas became central to the church so did his authority. The theory originated from a passage in II Peter: "But of this one thing be not ignorant, my beloved, that one day with the Lord is as a thousand years, and a thousand years as one day." (II Peter 3:8) The interpretation was taken to mean that mankind would live through six 1,000 year periods (or "days"), with the seventh being eternity in heaven. Medieval Christian scholars believed it was possible to determine the overall time of human history. Beginning with Adam, they added the age of each generation up to the time of Jesus recorded in the Bible. While the exact age of the earth was a matter of interpretive debate, they could agreed that humanity was in the last final thousand years, ie., the Sixth Age. The final Seventh Age, the Second Coming of Jesus, could happen at any time. Early Christians speculated freely on mans age. Abundant evidence was available for many interpretations in the Jewish traditions of the Old Testament. There are accounts for setting the date for the End of the World at the year 500. Hippolytus said that the measurements of the Ark of the Covenant added up to five and one-half cubits, meaning five and a half thousand years. Since Jesus had been born in the "sixth hour", or halfway through a day (or, five hundred years into an Age), and since five kingdoms (five thousand years) had already fallen according to Revelation, plus the half day of Jesus (the body of Jesus replacing the Ark of the Jews), it meant that five-thousand five-hundred years had already passed when Jesus was born and another 500 years would mark the end of the world. An alternative scheme had set the date to the year 202, but when this date passed without event, people expected the end in the year 500. By the 3rd century, Christians no longer believed the "End of the Ages" would occur in their lifetime, as was common among the earliest Christians.