John Wycliffe (c.1324-1384), first discussed yesterday, started his career as a respectable Oxford scholar and theologian. His religion and study taught him that wealth was not needed for a Christian life, and not appropriate for the clergy. This was not a radical idea, or new—Francis of Assissi had been preaching and embodying the ascetic life almost 200 years earlier*—however, his arguments and his public presence and patronage made him notorious.
It was after the conference at Bruges (mentioned briefly in the above link) that he seems to have decided he needed to make a more overt defense of his views. Wycliffe might have been fine keeping his views in the rather private academic arena, but when he was denounced and challenged in public by William Bynham of Wallingford Priory in Oxford, Wycliffe decided to go public with his Summa Theologiae in which he explained why the church should not have temporal authority, and that the king was above the pope in earthly matters. He followed this with De civili dominio (On civil lordship), in which he stated that if the church should abuse any of its temporal holdings, the king should take those holdings away; not to do so would be remiss. It was the strongest argument (and the most welcome, to members of the nobility) for the king's authority over the church.
The monastic orders, who benefited from the feudal system of rents and tenants, were understandably threatened by this, especially considering the patronage Wycliffe enjoyed from men like John of Gaunt, who was effectively the ruler of England during Edward III's decline. When Wycliffe was summoned before Bishop William Courtenay of London, he was accompanied by John of Gaunt, the Earl Marshal Henry Percy, other nobles, and even some friars of the orders that rejected personal possessions. Gaunt's presence cowed the bishop, and the gathering broke up without immediate consequence for Wycliffe. This pattern, of attempts to chastise or reign in Wycliffe being overwhelmed by his supporters, would be repeated more than once in the years to come.
In fact, Wycliffe's views were so popular in England that they sparked the anti-establishment movement called "Lollardy" about which it was supposedly said at the time "Every second man that you meet is a Lollard." It is certain that the citizens involved in the Peasants' Revolt were familiar with his views on equality, although he disapproved of their violence. It is ironic that Wycliffe's most powerful patron, Gaunt, was also one of the chief targets of the mob because of his aristocratic standing. It was not long after the Revolt that Wycliffe was officially being denounced as a heretic, which complicated his life but didn't stop him from writing. As well as other tracts and letters, he had one more major work he wished to produce that would shake the church to its foundations. He decided to do what had never been done before: translate the entire Bible into English.
*Umberto Eco's The Name of the Rose is remembered as a murder
mystery set in 1327 by many readers who have forgotten that one of the central
themes is the philosophical debate on the topic of the church and
material wealth.