It is extremely difficult to discuss in theoretical terms a movement (one cannot call it a theory or a doctrine) seeking simplicity. The movement is apparently continuous with the whole history of the Church. The history of Christian preaching is filled with recurrent cycles of antipathy to rhetorical form–Paul, Chrysostom, Peter the Hermit, the early Franciscans, the Lollards, the Quakers, and so forth. Perhaps any history of the rhetoric of preaching must insist that, whatever the visible evidence for an interest in praecepta at a given period of time, there was probably always a sizable group of nontheorists and antitheorists, actually engaged in preaching, who as a matter of principle rejected the idea of systematic theory. By its very nature it is the type of thinking that leaves few records.
James J. Murphy, Rhetoric in the Middle Ages