In the 20th century, two outstanding historians offered still more widely differing perspectives. The French historian Marc Bloch, arguably the most influential 20th-century medieval historian, approached feudalism not so much from a legal and military point of view but from a sociological one, presenting in "Feudal Society" (1939; English 1961) a feudal order not limited solely to the nobility. It is his radical notion that peasants were part of the feudal relationship that sets Bloch apart from his peers: while the vassal performed military service in exchange for the fief, the peasant performed physical labour in return for protection – both are a form of feudal relationship. According to Bloch, other elements of society can be seen in feudal terms; all the aspects of life were centered on "lordship", and so we can speak usefully of a feudal church structure, a feudal courtly (and anti-courtly) literature, and a feudal economy.