This essay reevaluates how and why, in the Old Arcadia ’s Third and Fourth Eclogues, Sir Philip Sidney imitates and revises specific aspects of two Spanish pastoral romances: Jorge de Montemayor’s Diana (ca. 1559–60) and Gaspar Gil Polo’s Diana Enamorada (1564). Each respective portion of the two Spanish works cited above relates to the protagonist shepherd Sireno. These representations of Sireno bear an important relationship to Catholic Christian piety. And each representation relates to the respective author’s specific concerns with political patronage. Sidney blends and transforms those two Spanish Sireno models as a means to invent both his pastoral persona Philisides and the wedding of Lalus and Kala in his Old Arcadia ’s Eclogues. By this means, Sidney invents moderate Protestant representations of affective individual piety and of marriage, each implicitly complementing Philipp Melanchthon’s theology of synergism. This thesis builds upon recent work on Sidney’s Defence of Poesy for a refined perspective on the continuity between theory and practice in his oeuvre. The argument also sheds new light on the relationship between Philisides’s political discourse and his discourse about love. In the Old Arcadia , these Eclogues’ non-allegorical representation of virtue and their rhetoric about marriage supplement the work’s main narrative plane rather than moralize it or illuminate it philosophically.