The notion of a distinct 'executive power' was famously employed by Locke and Montesquieu; but the term potestas executiva, coined by medieval canonists, had been adopted by the early sixteenth-century theologian Cajetan, who located it as regimen medium in his defence of papal power against a revived 'conciliarist' challenge. The distinction between legislative sovereignty and a power effectively executive (though not always so designated) was used in post- Reformation political controversy and in Bodin's République. From those beginnings it was developed by mid-seventeenth-century writers, from whom it passed to Locke; and the concept of the executive as a 'mediating' power was notably echoed by Rousseau.