This thesis aims to provide a new evaluation of the Histories of Agathias Scholasticus, one of the main sources for the reign of Justinian (527-565 CE). By contextualising the author and approaching his text with the tools of modern research, the thesis casts light on crucial aspects of sixth-century history, literature, and language. Through an interdisciplinary approach (history, literary criticism, philology, and linguistics), the research reappraises the Histories in all its complexity, focusing both on Agathias' specificities as a historian and on his role within early Byzantine historiographical production. Through a tripartite structure, constituted by a first section on myth, marvels and miracles in Procopius and Agathias, a second on Agathias’ ethnography, and a third on Agathias’ language, the thesis argues that this work is not just a classicising history written after the manner of Herodotus and Thucydides; not just a continuation of the Wars of Procopius, but also the work of an idiosyncratic, independent author who made idiosyncratic, independent literary choices.