AbstractThis paper describes and explains the central role of the principle of contractual liberty with the Jesuits of the early modern period. Designed as a diptych, it intends to clarify how the legal and the moral philosophical tradition mutually enriched each other at the threshold of modernity. The 'ius commune' helped the Jesuits in formulating the idea of negative freedom, only for that 'ius commune' to undergo a transformation itself under the influence of the scientific account of contract law that the Jesuits were to develop on its basis. First it will be shown how the Jesuits arrived at a moral problem-solving method capable of freeing man from unduely burdensome obligations before the court of conscience through the application of the law of property and procedure. Secondly, this paper will highlight the turn towards positive freedom through the Jesuits' elaboration of a general doctrine of contract as a mutually accepted promise centered around the notions of liberty, consensualism, and the image of the will as a private legislator.