This article proposes a political reading of ‘Cárcel de amor’, Diego de San Pedro’s masterpiece of Spanish sentimental fiction. First printed in 1492, ‘Cárcel de amor’ records the Spanish nation building by the fictional display of the politically coded conflict between the king and the knight. Each of these two figures in the novel personifies a different political order which can be defined according to Max Weber’s antithesis of ‘charisma’ and ‘rationality’: Whereas the knight Leriano embodies the charismatic leader, the king Gaulo, on the contrary, represents the rational state ruled by law. Thus on the level of political symbolism, the tragic love and death of Leriano means the disintegration of a charismatic body politic which unites the sovereign and his subjects in an emotional community. An allegory of love at the end of reconquista – ‘Cárcel de amor’ is also the first foundational fiction of the modern Spain as a rational-bureaucratic state.