One of the main aims of our project is to investigate whether clerical exile, and the related mobility and need to find alternative and often more informal sources of support outside institutional infrastructures, had the potential to lead to a particularly fertile environment for the diffusion of theological ideas, and other cultural products. In this regard, social network analysis can act as a theoretical guide. A particularly attractive network model here is Mark Granovetter’s famous model of ‘weak and strong ties’. The theory behind the model argues that each individual has an intimate social network of strong relationships or ties, and a less familiar ‘acquaintance’ network of weak ties. A network of weak ties, however, is better equipped to diffuse information and ideas, because it connects disparate subgroups and ‘outliers’ (actors only connected to a social network through another actor), while a network of strong ties is more insulated and tends to share the same information. The most successful networks have a variety of weak and strong ties. The most important actors in this model are those who ‘sit’ on the weak tie, and therefore control the flow of information between different groups (also called brokers).
Reading recently about how fifth-century Church Historians reported on the spread of what they called ‘Arianism’ in the early fourth century I noticed a particular set of relationships that fit Granovetter’s model perfectly. According to the Ecclesiastical Histories of Rufinus, Sozomen, Socrates and Theodoret (all apparently drawing on the lost work of Gelasius of Caesarea), Arius – condemned at the Council of Nicaea in 325 for claiming Christ the son was created by God the father, and subsequently exiled by Constantine – was recalled by Constantine in 327 under influence of his favourite sister, Constantia. The Church Historians relate how Constantia was persuaded by an unnamed Arian presbyter (according to Sozomen on instigation by the pro-Arian bishops Eusebius of Nicomedia and Theognis of Nicaea), who was a member of her household and her intimate confidant, that Arius’ condemnation at Nicaea had been unjust. While she never actively pleaded with Constantine for Arius on these grounds, she commended the presbyter to her brother on her deathbed, at which point he passed into the emperor’s household, where he could repeat his assertions and eventually arrange that Arius and his companion, the deacon Euzoïus, were granted an audience with the emperor leading to their recall. Theodoret elaborates on even further unfolding of events: The same presbyter (in Theodoret’s version without having revealed his Arian credentials to the emperor) was present also at Constantine’s death, and, with no immediate relatives at hand, the emperor entrusted his will to him, for delivery to his son Constantius II. As a result the presbyter, together with the will, now passed into Constantius’ household, where he (again on instigation by Eusebius of Nicomedia and Theognis of Nicaea) corrupted the new emperor’s mind against the champions of Nicaea.
Using a basic Social Network Analysis programme (NodeXL), the described social relationships can be calculated and visualised like this:
The size of the nodes in this graph is based on so-called ‘between-ness centrality’, the degree to which each actor connects other actors across the network. Those with the highest ‘between-ness centrality’ are the brokers who sit on the ‘weak ties’. The graph shows very nicely that the Arian presbyter is a broker between two strongly connected subgroups, via Constantia. What the graph cannot show is that the Arian presbyter both controls how ‘heretical’ information is passed on, and is himself the heretical ‘product’ being passed on.
Unfortunately, the Church Historians’ version of Arius’ recall is an obvious fabrication, and would not stand the test of ‘real’ social network analysis. What was true about it was Constantia’s acquaintance with a number of Eastern bishops who are also recorded as Arius’ supporters, first of all Eusebius of Nicomedia. Eusebius had become bishop of Nicomedia in 318, the same time that Constantia, then married to Constantine’s co-emperor Licinius, had moved to the imperial capital in Bithynia. Later, at the Council of Nicaea, Constantia seems to have persuaded Eusebius, Theognis of Nicaea and Maris of Chalcedon, to subscribe to its Homoousian formula, against Arius’ teachings, although they refused to condemn him. In 325 Constantine would probably have found his sister’s connections and familiarity with Eastern bishops immensely valuable, and of course they helped him at first to create unity at the Council of Nicaea. Constantia’s acquaintance with Eusebius of Nicomedia only became a problem after the Nicene triumph later in the fourth century and the transformation of Eusebius into an arch-heretic, as did Constantine’s volte-de-face, when he recalled Arius in 327.
The fifth-century Church Historians, looking to explain the apparent and to them puzzling inconsistency of Constantine’s dealings with the ‘Arian’ faction and his son Constantius’ ‘semi-Arian’ sympathies, therefore turned to the record of Constantia’s network and added some embellishment. Aside from the invention of the presbyter, it is remarkable how in their story the primary role of imperial women as transmitters of dynastic legitimacy and issue — a role that was endlessly celebrated in late antique imperial imagery — is mirrored and subverted, by representing Constantia as a conduit of religious contagion and associated personnel to the next imperial generation. The presbyter’s anonymity conveniently also served to exonerate Constantia, but more so her imperial relatives, from willing or conscious complicity. In face of a strong female presence at the fifth-century Constantinopolitan court, Constantia’s example may also have served as a warning against a too close overlap between court affairs and ecclesiastical business, and of the role of (by virtue of their female nature gullible) imperial women as gatekeepers to the emperor.
Constantine’s wavering attitude to Arius and his supporters still puzzles historians today. What is significant is that fifth-century Church Historians, just like modern social network analysts, suspected that social relationships, and above all ‘strong’ links, such as kinship, and ‘weak’ links such as that presented by the clerical ‘interloper’, played a role in shaping the emperor’s actions. They also feared that through these social links informal power, such as that wielded by Constantia and her household, may cut across formally instituted power, such as that of emperors, another theory they share with social network analysts. Their ideas on how information circulated may hence well have been true, even though it was certainly a much more complex scenario than they imagined. Characteristically for their time, the Church Historians had a reductive view on the spread of what they thought of as ‘heresy’, blaming a woman and her anonymous and lowly household dependant, as such preserving the memory of the imperial men, above all that of Constantine, untouched.
 M. Granovetter, Getting a Job, Cambridge, Mass., 1974.
 Rufinus, Ecclesiastical History 10.12; Socrates, Ecclesiastical History 1.25; Sozomen, Ecclesiastical History 2.27; Theodoret, Ecclesiastical History 2.3.