The text was written for teaching purposes by Peter of Poitiers, a chancellor at Paris University from 1193 to 1205. His intention was to create a brief treatise to be of use to his students and a study aid for the poor clergy unable to pay for books. He therefore presented the Old Testament tales in the form of genealogical trees on a strip of parchment to be pinned to the classroom walls so that their entire content could be seen at a glance. The work was highly successful and very widely read for at least fifty copies dated between the 13th and 15th centuries have survived.
Because of the complexity of the characters and situations told in the Bible he produced a summary of the most significant ones in the history that culminated in Christ. Peter of Poitier’s Genealogia Christi or Compendium is organised in six historical periods, known as the six ages of the world, which stem from a very ancient theological tradition based on the Bible (Genesis 5: 1, 6: 9 and Matthew 1: 1-17). The first five ages open with five Old Testament characters: Adam, Noah, Abraham, David and Sedecias. The sixth age is heralded in by the annunciation of the birth of Christ and ends with a Crucifixion scene showing, in addition to Christ, the Virgin Mary and St Francis of Assisi.
A range of colours is used to differentiate certain aspects such as, for example, the sex of the characters (women’s names appear inside circles surrounded by green, and men’s in circles surrounded by red) and their social class (red and ochre being used for monarchs, and blue for prophets). Similarly, each of the ages, located along the central trunk stretching from Adam and Eve to the Crucifixion, into which the history of the world is divided, appears in a different colour: the first age is ochre, the second red, the third green, the fourth red, the fifth blue and the sixth golden yellow.