Production of more food--the system allowed for more food to be produced which fed the workers in an industrial economy.
The 'four-field system' rotates crops between the 4 fields no longer needing to keep one empty because one of the crops would replenish the field with nutrients while the others take nutrients away from the fields. <span />
Shi'a Islam or Shi`ism (from the Arabic word شيعة, Persian: شیعه) is the second largest school within Islam. Shi'a Muslims adhere to the teachings of the Islamic prophet Muhammad and his Ahlul Bayt (family). Shi'as believe that the Imam – their preferred title for the political and religious leader of the Muslim community must belong to the direct lineage of Muhammad through his daughter Fatima and her husband (and Muhammad's cousin), Ali ibn Abi Talib (Imam Ali, the fourth caliph). The Imam is regarded as sinless and infallible and appoints his successor (except within the Zaydi sub-group, in which he emerges). The Shi'as reject the first three caliphs in Sunni Islam as usurpers of Ali's Imamate. The theme of lineage and infallibility of the Imam developed within Shi'a Islam, as well as the idea of a hidden Imam who will bring God's judgment in the Last Days. There are several sub-divisions. Some Shi’a, such as the Aga Khan Ismailis recognize a living Imam. For the majority group, the Imam is now "hidden" but will return as the Mahdi. Relations between 'Shi'a and Sunni Muslims have been strained although efforts at reconciliation have also been made. The differences between the two schools can be maximized or minimized, depending on the agenda of the commentator. Shi'a have often lived as minorities and as such have experienced persecution. Since the beginning of the Safavid Dynasty it has been the State religion in Iran, where this status has often led to confusion between religion and the pursuit of Iranian national goals, which have sometimes involved a desire to restore Persia's ancient power and prestige in the region.
<h3>Etymology</h3>
The term Shi'a comes from the Arabic word شيعة Shi'a. The singular/adjective form of this name is Arabic shi`i شيعي.
"Shi'a" is the short form of the historic phrase shi`at `Ali شيعة علي, meaning "the advocates of Ali." Sunni and Shi'a sources trace the term to Muhammad himself. The phrase Shi'a of Ali was historically a title given by Muhammad and later by his descendants in praise of Ali's followers and that of the Ahlul Bayt (house of the Prophet’s family). Rippin (1991) refers to Shi'a as an "alternative vision of Islamic identity" (Rippin 1991, 103-116).
