A broader definition of feudalism, as described by Marc Bloch (1939), includes not only the obligations of the warrior nobility but the obligations of all three estates of the realm: the nobility, the clergy, and the peasantry, all of whom were bound by a system of manorialism; this is sometimes referred to as a "feudal society". Since the publication of Elizabeth A. R. Brown's "The Tyranny of a Construct" (1974) and Susan Reynolds's "Fiefs and Vassals" (1994), there has been ongoing inconclusive discussion among medieval historians as to whether feudalism is a useful construct for understanding medieval society.