The aim of the article is an overview of the reasons who led in 397 Simplicianus of Milan to request to Augustine a clarification about Origenian theological and scriptural interpretation on freedom and grace. The principal hypothesis is that Simplicianus was waiting for a response from Augustine in support of Milan's ‘Origenism': the Ambrosian purpose was in fact the creation of a local strong church, both politically and theologically, supported by ‘exportable' rational principles (Milan, capital of a new, ‘enlightened', and universal Christianity). This contribution focuses on the “political” use of Origenism in the ‘neo-platonic circle' of Milan, relevant in showing its religious identity in the struggle for supremacy of the imperial city and church. This essay also draw on a reflection about the re-foundation of the Catholic church against Arianism and about the Hellenization of Latin Christianity (Marius Victorinus, Simplicianus, Ambrose and the first Augustine).