The question of sources concerns not only the origin of individual stories, but also the structure and organization of the various cycles of myth. The Greek mythological tradition, as summarized in a broadly representative manner in the Library, is in many respects a peculiar one. It is dominated to an unusual degree by heroic mythology, and the material from heroic legend is organized in such a way that it provides an unusually coherent pre-history of the regions covered. As has been remarked, stories are rarely located in an indeterminate past; each is fitted into its appropriate place, whether in relation to the history of a specific place and the successive generations of its ruling family, or to the development of a great adventure or the life history of a major hero. For the most part, this systematization was not the work of the scholarly mythographers of the Hellenistic era, but was achieved at a relatively early period by the epic poets and by prose writers who regarded themselves as historians rather than mythographers. Indeed, the beginning of the process by which the mass of often mutually inconsistent myths in the oral tradition was ordered into a coherent pseudo-historical pattern can be traced to the earliest Greek literature to be recorded in writing, the Homeric epics and Hesiod’s Theogony, and the process was brought to fruition in the works of the fifth-century mythographer-historians—precisely the sources most frequently cited in the Library. First we must consider the nature of these early sources and their contribution to this process, and then how the author of the Librarymade use of them.

Until the development of prose literature in the latter part of the sixth century, Greek literature was exclusively poetic, and the richest sources for myth and legend were the works of the epic poets. The earliest epics to survive, the two Homeric epics and Hesiod’s Theogony, were probably written about the same time towards the end of the eighth century. Although they belong to the same broad genre, the poems attributed to these authors are quite different in nature. Homer was a story-teller on a grand scale and each of the Homeric epics is constructed on the basis of an overall plot running through the whole poem. But Hesiod organized his Theogonyon a genealogical basis; and generally speaking, in a genealogical poem of such a kind the stories associated with the various figures are inserted successively as the figures are introduced in the genealogies, and the narratives are relatively brief and self-contained. These contrary approaches can be related to the two main ways in which the mythical material is organized in different parts of the Library, the narrative ordering in the histories of great adventures like the voyage of the Argonauts and the Trojan War (or in the life of Heracles), and the genealogical ordering in large stretches of the histories of the great families, where we find an alternation between genealogical sections and narratives recounting the stories associated with the heroes and heroines as they are successively introduced in the genealogies. We will examine first how the works of the epic poets who could be regarded as the successors of Homer contributed to the establishment of standard accounts of the greater mythical adventures, and then how the Hesiodic approach was extended in a later epic to cover heroic mythology, resulting in the development of an all-embracing genealogical system.

The main action of the Iliadcovers only a few days in the tenth and final year of the Trojan War, and the Odysseydescribes the return voyage of only one of the Greek heroes, although both poems assume a much broader background of Trojan myth and they contain many allusions to stories not directly covered in the poems themselves. The exceptional quality of the Homeric poems seems to have impressed itself on their audience from the beginning, and it is understandable that poets in the century following their composition should have wished to compose epics covering the elements in Trojan mythology not already covered by Homer, and, in effect, fill in the gaps. And so it came about that a cycle of epics was composed which, taken together, built up a sequence narrating the entire history of the Trojan War. Although only a few fragments have survived, we know their general contents from a series of summaries attributed to a certain Proclus, and can see how they were constructed around the Homeric epics. Thus the origins of the war and all events up to the angry withdrawal of Achilles which marks the beginning of the Iliadwere covered in a single long epic, the Cypria;and then three shorter epics (partly overlapping in content) continued where the Iliadleft off, covering the final period of the war and the sack of Troy. Then the Returnstold of the return voyages of the surviving Greek heroes, except for Odysseus, and last of all, the later history of Odysseus was recounted in the Telegonia, which formed an eccentric supplement to the Odyssey. Although there is reason to think that by Homeric standards the artistic quality of these poems was not high, they were of great importance from a mythographical viewpoint for the part that they played in the establishment of a canon of Trojan myth. By selecting and ordering material from the oral tradition and earlier lays, and ‘fixing’ it in long poems which were transmitted to future generations, the authors of such epics made a major contribution to the formation of standard histories of adventures like the Trojan War. The account of the war in the Libraryis ultimately dependent on these epics for its general structure and much of its contents. Other epics composed in the seventh century or somewhat later fulfilled a similar service with regard to other mythical episodes, such as the Theban Wars, or the voyage of the Argonauts (although, as we shall see, Apollodorus followed a Hellenistic epic for that adventure).

In his Theogony, Hesiod sought to organize the traditions concerning the gods into a coherent pattern by developing the comprehensive genealogical system which forms the basis of his poem. Beginning with a mythical cosmogony presented in genealogical terms, he tells of the origin and descent of the earlier gods and the establishment of Zeus as supreme ruler, and concludes with a catalogue of Zeus’ marriages and his offspring by his wives and other women. A supplement was added later which includes a catalogue of the children born to goddesses by mortal men. As a story-teller, Hesiod is short-winded and often clumsy, although his material is naturally of great interest. The approach adopted by Hesiod is largely determined by the peculiar nature of his subject matter; but later, probably in the sixth century, another poet composed a continuation to his poem extending the same approach to heroic mythology. This epic, which survives in fragments only, is known, somewhat misleadingly perhaps, as the Catalogue of Women, because the origin of each line is traced to the offspring of a god by a mortal woman. Its importance for Greek mythography cannot be emphasized too strongly; for it was here that the heroic genealogies were first ordered into a coherent pan-Hellenic system. The pattern of heroic genealogy which we find in the Libraryis still similar in general outline (although, of course, it often reflects later developments). And the Catalogueoffered far more than sequences of names; for most names suggest a story, and the relevant narratives were inserted at the appropriate points in the presentation of the genealogies. This approach was subsequently adopted by prose mythographers and, as we have observed, it is in evidence in many parts of the Library.

Historians were prominent amongst the earliest prose writers. Some concerned themselves with purely local matters, but others (including those mentioned amongst the authors most frequently cited by Apollodorus) had broader ambitions and covered the traditions associated with many parts of the Greek world. They could not extend their researches any distance into the past without engaging with what we would regard as myth; and in the present context, it is their contribution to mythography which interests us. But they regarded themselves as historians, and while they were not always totally uncritical, they were willing to accept myth and legend as reliable sources of historical truth. In this respect, they differed from the scholarly mythographers of the Hellenistic era, who were critical in their attitude to myth and regarded mythography as a separate area of investigation. These earlier authors, whose qualities must be judged from fragments and testimonies, are sometimes referred to as logographers to distinguish them from more critical historians like Herodotus and Thucydides; but since this term (which simply meant ‘prose writers’ in ancient usage) can be misleading if it is thought to describe a specific school of historians, it is safer to describe them merely as historians (or mythographer-historians or chroniclers).