Ulpian, a jurist born in Tyre, writes more than 140 books on civil law and the praetorian edict that would later constitute between a third and 40% of all citations in Justinian's Digest — the highest proportion of any classical jurist. Appointed praetorian prefect by Alexander Severus, he attempts to reform the abuses of the Praetorian Guard and is killed by mutinying soldiers in the emperor's own presence.