 If there is a theme to this history, it is perhaps the development of political  liberalism,  though, to be sure, ideals of  constitutionalism  (see, e.g., Tierney 1982, Pennington 1993a, Lee 2016),  civic humanism,  and  republicanism  (on these last two, see, e.g., Skinner 1978; Hankins 2000) may be found among different medieval  authors.[79]  The liberal trend was helped, perhaps paradoxically, by the close interweaving of religion with other threads of medieval life. This meant not only that religion influenced all aspects of life, but also, reciprocally, that the other departments of life influenced religious thinking. The influence of the Roman Law and Aristotle, and of the culture of late antiquity familiar to the Fathers of the Church, also meant that ideas originating outside the framework of the Christian religion had an impact on religious thinking. The duality between kingship and priesthood (perhaps originally due merely to the fact that Christians had no political power), and the conflicts that resulted from that duality, meant that religious thinking had to accommodate the concerns of powerful people who were not officials in the religious institutions.