as the Ius novum ("new law") or middle period covers the time from Gratian to the Council of Trent (mid-12th century–16th century). The spurious conciliar canons and papal decrees were gathered together into collections, both unofficial and official. In the year 1000, there was no book that had attempted to summarize the whole body of canon law, to systematize it in whole or in part. The first truly systematic collection was assembled by the Camaldolese monk Gratian in the 11th century, commonly known as the Decretum Gratiani ("Gratian's Decree") but originally called The Concordance of Discordant Canons (Concordantia Discordantium Canonum). Before Gratian there was no "jurisprudence of canon law" (system of legal interpretation and principles). Gratian is the founder of canonical jurisprudence, which merits him the title "Father of Canon Law". Gratian also had an enormous influence on the history of natural law in his transmission of the ancient doctrines of natural law to Scholasticism. Canon law greatly increased from 1140 to 1234. After that, it slowed down, except for the laws of local councils (an area of canon law in need of scholarship), and secular laws supplemented. In 1234 Pope Gregory IX promulgated the first official collection of canons, called the Decretalia Gregorii Noni or Liber Extra. This was followed by the Liber Sextus (1298) of Boniface VIII, the Clementines (1317) of Clement V, the Extravagantes Joannis XXII and the Extravagantes Communes, all of which followed the same structure as the Liber Extra. All these collections, with the Decretum Gratiani, are together referred to as the Corpus Iuris Canonici. After the completion of the Corpus Iuris Canonici, subsequent papal legislation was published in periodic volumes called Bullaria. In the thirteenth century, the Roman Church began to collect and organize its canon law, which after a millennium of development had become a complex and difficult system of interpretation and cross-referencing. The official collections were the Liber Extra (1234) of Pope Gregory IX, the Liber Sextus (1298) of Boniface VIII and the Clementines (1317), prepared for Clement V but published by John XXII. These were addressed to the universities by papal letters at the beginning of each collection, and these texts became textbooks for aspiring canon lawyers. In 1582 a compilation was made of the Decretum, Extra, the Sext, the Clementines, and the Extravagantes (that is, the decretals of the popes from Pope John XXII to Pope Sixtus IV). Ius novissimum