In the De decretis Athanasius claims that Arius ‘copied’ and ‘learned’ from Asterius. This study explores how this could have happened by arguing that in the writing of his Thalia Arius was influenced by Asterius’ Syntagmation. Besides complicating the literary and theological relationship between Arius and Asterius, this reconstruction provides the clearest evidence for the new perspective on Arius which has emerged in recent revisionist scholarship, and which argues that he is best understood as embedded within a theological tradition and as a catalysing participant in its efforts to articulate a theological vision. By dating the Syntagmation to about 322 and the Thalia to about 323 this study also gives qualified support to Rowan Williams's dating of some pre-Nicene events and discredits a recent attempt to position Asterius as having had a formative influence on Arius.