"De temporibus", or "On Time", written in about 703, provides an introduction to the principles of Easter computus. This was based on parts of Isidore of Seville's "Etymologies", and Bede also included a chronology of the world which was derived from Eusebius, with some revisions based on Jerome's translation of the Bible. In about 723, Bede wrote a longer work on the same subject, "On the Reckoning of Time", which was influential throughout the Middle Ages. He also wrote several shorter letters and essays discussing specific aspects of computus.