The non-specialist, forewarned, will probably find the differences in nuance between historical accounts written from court and from severely Christian perspectives more illuminating than confusing. Two other types of evidence supply contrasts or supplements to what is on offer from Byzantine narratives. Firstly, accounts penned by persons with no ambition whatsoever to be considered ‘Roman’ reveal much about Byzantine history, as the frequent citations from them in chapters below will attest.Here one may note that several conflicts or confrontations between the empire and external rary sources that were composed by third parties. A prime example is the Arab conquests in the seventh century, recounted by an eyewitness Egyptian bishop, John of Nikiu, and by the contemporary Armenian author now known as Sebeos, as well as by later Byzantine and Muslim writers.45 Other examples might include the encounters, diplomatic and military, between Byzantine emperors and the emergent German and Rus leaderships of the second half of the tenth century,46 while the First and Fourth Crusades each inspired a classic Byzantine set piece as well as vivid eyewitness accounts from westerners.47 Adversarial situations and battles are the stuff of narrative, and outside observers or travellers – other than ninthand tenth-centuryMuslim writers48 – have less to say about peaceful forms of exchange between Byzantium and its neighbours, or about the internal structure of the empire. This brings us to a second type of evidence that may draw the newcomer closer to the inner workings of the empire. It is neither narrative nor descriptive of Byzantium, but consists of didactic texts ranging from general theoretical considerations, maxims and counsel to precise technical instructions. In some ways these texts resemble the Byzantine source-material discussed above, seeing that they could be termed idealising or aspirational. They prescribe how things ought to be done, rather than describing things as they were. They do not amount to archival data, functioning organs of the empire in use. But the durability of some of the texts suggests that they appeared relevant, of potential invocation or practical application. The format could also allow a writer to voice opinions on contemporary issues of politics and society as well as on the abstract or the technical. This in itself gives them historical source value. Furthermore, some touch on issues of life and statecraft that seldom ranked as suitable subject-matter for formal historical compositions. Only a few examples will be cited here, not least because the Byzantines closely followed – and copied – the instructions of the ancients on so many subjects, grammar, mathematics, medicine and warfare among them. Attempts were, however, made to update received wisdom in light of changing circumstances; occasionally a wholly new text was composed. Fortunately, the Byzantines’ more original texts and major revamps tend to attract English translators. A notable example of political thought couched as recommendations to an emperor dates from Justinian’s era, Agapetus’ Mirror of princes. Ernest Barker translated extensive sections, together with excerpts from orations and other texts bearing on political thought for eras up to the last decades of the Byzantine empire. Among the works translated and commented on by Barker are Gemistos Plethon’s ‘Address toManuel Palaiologos on affairs in the Peloponnese’, and his ‘Treatise on laws’.49 One duty of the emperor himself was to set a moral lead, and his injunctions could have the status of solemn precepts or law. Leo VI expanded on this notion not only with his sermons, but also with other writings, including two treatises on military tactics, drawn largely from earlier texts. One of his main sources, the Strategikon of Emperor Maurice, is available in English as is the ‘constitution’ on naval warfare taken from Leo’s Tactica, but the rest of Leo’s oeuvre awaits its translator.50 Leo’s son Constantine went further still, commissioning a lengthy series of excerpts from classical and early Byzantine historical texts, each collection devoted to one topic, for example ‘plots against emperors’, ‘virtue and vice’ and ‘instructive sayings’. Constantine thereby displayed his unique access to book-learning, but his preface is addressed to ‘the public’. The texts are mostly in fairly straightforward Greek, and the lists of excerpted authors provided at the start of, probably, each set will have facilitated quick consultation. The ‘public’ probably consisted in practice mainly of persons in state service, who might benefit from picking up guidebooks, user-friendly both for practical expertise and for the broader ethical and cultural hinterland of empire.One of the few extant sets of excerpts is devoted to ‘embassies’, presumably being designed for persons involved with diplomacy in one way or another. The lengthy excerpts from a sixth-century historian of diplomatic exchanges are coherent enough for them to have been published in translation, partially reconstructing the now-lost original.51 Constantine VII’s regard for the written word as a means of enhancing good form and order is shown by the compilation on court ceremonies he commissioned. His sideswipe at Romanos I Lekapenos (920–44) for shortcomings in ceremonial (see above, p. 19) hits on a fundamental question: how to maintain stately continuity while accommodating the dynamics of power shifts, finding room for one-off events and exceptional circumstances. The Book of ceremonies, while invoking the harmony of movement that God gives to all creation, draws partly on memoranda arising from particular occasions. Scholars have detected the layers of adaptation and improvisation underlying this, and the English translation now in preparation should make this plain.52 Constantine’s concern to uphold imperial decorum and exclusivity at all events emerges equally from the treatises on imperial expeditionary forces compiled for him.53 Most striking of all, however, are the prescriptions for divide-and-rule and other techniques of statecraft in his De administrando imperio.54 Romilly Jenkins’ translation conveys the generally plain style both of the source-materials assembled by Constantine and his aides, and of the emperor’s own written ‘doctrine’. We glimpse the Realpolitik behind the scenes, the presupposition that the barbarians for whom the grand receptions were staged were driven mainly by greed, fear and mutual rivalries. A ruler’s personal assumptions and calculations about his polity are captured, albeit in snapshot form, to a degree virtually unparalleled among pre-modern states. And all in the name of taxis.