Abstract
Legal scholars often conceive of law as though it possessed physical and mechanical properties: it can be rigid or flexible, heavy or light, narrow or broad. The very word ‘law’ embodies this imaginary logic: it evokes a straight line, the right path, and rectitude. It is often claimed, however, that the Romans did not speak of *directum* but of *ius*, and that the idea of ‘law’ only became established in the Middle Ages. This course demonstrates, on the contrary, that the metaphor of rectitude was already deeply ingrained in the language of Roman jurists. Studying it therefore provides a better understanding of the construction of the legal imagination over the long term.
But the law is not conceived merely as a line: it is also conceived as a burden. By comparing Cicero’s *Pro Roscio Amerino* with a text by the jurist Papinian, we gain an awareness not only of the deep roots of this conception, but also of its transformations. In Cicero’s work, the weight of commitment remains within the moral order: the orator could always abandon Roscius’s defence, even at the cost of losing his credibility and the trust of others. In Papinian’s work, the law transforms this commitment into a constraint: the agent remains bound by the weight he has assumed by pledging his fides.
Thus, the metaphors of the line and the weight are not mere embellishments: they structure the way in which jurists think about and interpret the law.
