The Flemish humanist Justus Lipsius’ (1547–1606) two works, the Constantia and the Politica are analysed here as examples of the redefinition of the boundaries between public and private brought about in the late sixteenth century. This was the result of many factors, among which the wars of religion was perhaps the most prominent. Lipsius’ experience of the wars, his work, his associated flights and confessional switches make him an ideal commentator on the disjunction between public and private. In the two works under consideration, prudence and constancy are ascribed to the two domains while the different traits of the two virtues reflect on the different moral framework of public and private. The moral superiority of the private realm is associated with the divine through man's personal relationship with God following the Stoic notion of the kinship between human and divine reason. Prudence, an entirely human and temporal virtue, equips man in his conduct through the instability and depravity of temporal/human affairs. Man can still be constant, however, and maintain his morality and religious integrity in private. Thus, in the context of the continuous religious tension and political instability the moral implications of the distinction between the two realms render the discourse of the relationship between public-private and divine-temporal into an issue regarding the limits of ecclesiastical and political jurisdiction.