Hexameron

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The Hexameron — from the Greek hexaēmeron, “the six days” — is the body of Christian commentary devoted to the six days of creation narrated in the first chapter of Genesis. The word names both the biblical episode and the interpretive genre that grew up around it: a sustained effort to read the opening lines of scripture as a coherent account of how the world was made, and to square that account with what the ancient world thought it knew about nature.

The episode itself has a strong internal architecture, which the commentators worked from. The six working days fall into two parallel triads. The first three separate and form three realms — light divided from darkness, the firmament dividing the waters above from the waters below, the lower waters gathered so that dry land and vegetation appear. The second three fill those same realms in matching order: the sun, moon, and stars for day and night; the creatures of sea and air; and the land animals and humankind. The whole is crowned by the rest of the seventh day, which God blesses and hallows. This pattern of forming and then filling gives the account its sense of order and completeness, and it would later become the textual basis of one whole modern reading of the chapter.

The Christian genre’s founding text is a set of nine homilies preached by Basil of Caesarea in the fourth century, delivered to a congregation and only afterward collected — though Basil was not working in a vacuum. He had Jewish predecessors: a lost treatise by Aristobulus of Alexandria, and, surviving, Philo’s On the Creation of the World, which had already read Genesis through Greek philosophy. Basil’s homilies are the earliest extant Christian Hexaemeron rather than the first commentary on the six days as such. He took the bare Genesis sequence and expounded each day in turn, folding in the natural science of his age — the elements, the motions of the heavens, the habits of animals — and using the late creation of the heavenly bodies on the fourth day to argue against astrology. Standing between the allegorical school of Alexandria and the literal school of Antioch, Basil sided with the literal: grass, for him, was grass. His brother Gregory of Nyssa completed the project with a treatise on the sixth day, the making of man, that Basil had left aside. The work was widely read and quickly imitated, translated into Latin, Syriac, Armenian, and more.

Ambrose of Milan carried the form into the Latin West, producing a Hexameron that leaned heavily on Basil but reworked him freely, threading in Virgil and Cicero rather than translating. Augustine returned to the six days repeatedly, in at least four works across his life, most searchingly in The Literal Meaning of Genesis. There he argued that God created all things at once, instantaneously, and that the “days” are therefore not a sequence in ordinary time but a framework expressing the order in which created things stand before God — noting, too, that six is a perfect number, the sum of its parts. To reconcile an instantaneous making with a world that visibly unfolds over time, he proposed the rationes seminales, the seminal reasons: causal potencies God planted in matter at the first instant, which afterward develop into the visible forms of things as conditions allow. The form persisted for a millennium, taken up by Bede, by Peter Abelard, and, in the thirteenth century, by Robert Grosseteste and Bonaventure.

What unified these writers was a shared assumption rather than a shared conclusion. They held that Genesis described real events, and that the natural world, rightly understood, would confirm rather than contradict the text. Their disagreements were correspondingly sharp: whether the six days were literal twenty-four-hour periods or a figure for an instantaneous creation; whether the “waters above the firmament” were physical water or something else; how the account related to the cosmologies the Greeks had built. Two reading traditions ran through the whole — the Antiochene literal and the Alexandrian allegorical — though most of the Fathers in practice combined them, taking the events as real while reading further meanings out of them. Grosseteste’s contribution shows the stakes precisely: rather than simply absorbing the newly available Aristotle, he used the Hexaemeron to defend creation in time against Aristotle’s argument, in the Physics, for an eternal world, reconciling conflicting Greek and Latin authorities instead of surrendering to either. The Hexameron was, in effect, the arena in which late-antique and medieval Christianity negotiated between revelation and the philosophy of nature it had inherited.

That inheritance was substantial, and behind it stood Plato’s Timaeus, in which a divine craftsman shapes a disordered matter into an ordered cosmos. The commentators themselves felt the nearness of that picture and worked hard to mark where their maker differed from the Platonic one — above all in creating from nothing rather than ordering what already was. The resemblance belongs to the felt tension of the tradition, something its writers registered and pushed against, rather than to any lineage they would have claimed. The old Hexameral question outlives them. It survives wherever the six-day account is weighed against natural knowledge: in the strictly literal reading of six ordinary days; in the day-age reading, which takes each “day” for a long geological age; and in the literary-framework reading, which treats the two parallel triads as a way of ordering God’s acts topically rather than as a chronology. The last of these regularly cites Augustine — whose days were never a timetable — as its ancient warrant. Read across its long history, the Hexameron is less a single doctrine than a recurring question: what it means to say that a world had a beginning, and that the beginning can be told.

→ In the library: Plato — Timaeus (Jowett, 1892)

→ Related: Comparative Flood Myth · Abyss · Gnosis