Medievalists well know that the “evangelical poverty” movements of the 12th–13th centuries, preaching a life of poverty based on that of the apostles, were as much a response to the demands of religious reform as they were to the social and economic changes of the times. They fully expressed a desire for another, different life. In the 15th century, other movements, in particular in Bohemia, developed a discourse and practice meant to embody the early Church. Opposite them, the charismatic preachers of Observance, who favoured the return of a regular clergy and a closer compliance with the Rule, were also, hand in hand with civil powers, active upholders of a religious reform that through deep social regeneration would build a societas christiana characterised by uniformity and obedience. These movements were at least partly underpinned by what we now call religious revivalism, i.e. the assertion, through demonstrative and emotional piety, of a faith that is more secularly active and less of a customary routine, invigorated by conversion and a call for repentance, literal readings of the Scriptures and a desire to pass on their message. In this they bear the same equivocal features as those movements that emerged in Germany, in the current of the Lebensreform, at the turn of the 19th–20th centuries: attempts to establish whether they were manifestations of “modernity” or instead reactions against “modernity” are largely futile and soon generate contradictions. By contrast, what is striking is the common store of themes and means that can be evidenced, especially for the specific context of the 1920s when certain German regions were toured by itinerant preachers, the “Inflation Saints” (Inflationsheilige), who brought into play the same processes as the Wanderprediger of the late Middle Ages.Mass effects arising from the exertions of preachers (miracles, conversions, influence on social and public life) have thus recurred down the centuries. This return prompts medievalists, or more generally historians specialised in religion, to put into perspective certain movements that have appeared in the contemporary period, in particular in Germany, where the economic, social and moral crisis lent the early 20th century aspiration for the anders leben a strongly religious or even messianic, millennialist hue. This historical approach helps to assemble the constitutive parts of a grammar of religious revival, which can lately be discerned in the “neo-pentecostal” movements that have flourished over the last four decades.