Both of the ideas presented in this chapter have roots in late Antique Neoplatonism, but their development is distinctively medieval. Boethius framed a fresh definition of eternity, and if Pseudo-Dionysius the Areopagite did not invent the term hierarchy, he put a stamp on the term that was to carry it through many centuries in many contexts. Eternity and hierarchy can be regarded as something like the temporal and ontological coordinates of medieval thought, with eternity embracing all time and hierarchy vertically grading all beings. The two ideas are at any rate both presuppositions and problems for much of what follows in this volume.

ETERNITY (JOHN MARENBON)

What did medieval thinkers mean when they called God “eternal”? We now give two main senses to “eternity”: perpetuity (“Peternity”) – when something lacks (Pi) a beginning or (Pii) end or (Piii) both; or (“O-eternity”) being altogether outside and unmeasurable by time. Philosophers usually explain O-eternity as “timelessness.” Something is timeless, they say, when it is without either extension or position in time, and so no sentences that contain time references of any sort are true of it. On this account, nothing can be both P-eternal and O-eternal, since a P-eternal thing exists at many times (all times in the case of Piii), whereas an O-eternal thing exists at no time.