Aeternitas
aeternitas
The classic definition of eternity, forged by Boethius in Book V: the entire and simultaneous possession of a life without succession, without beginning, middle, or end. It stands in contrast to temporal duration, which is never possessed in its entirety—the next day is still lacking when the previous one is already lost. Eternity is not a very long time: it is a mode of being where everything is held all at once. To be distinguished from Augustine’s [*distentio animi*](/lexique/distentio-animi), time experienced as the stretching and scattering of the soul; and from mere infinite duration, for an endless succession remains a succession, not a simultaneous possession.
L’éternité est la possession entière et parfaite d’une existence qui n’a ni commencement, ni milieu, ni fin.
Aeternitas. Boethius seeks to understand how God knows the future without nullifying freedom—and to do so, he must first define what divine eternity is. His answer—interminabilis vitae tota simul et perfecta possessio—echoes through all subsequent theology. The formula hinges on a single pivotal word: possession. The eternal does not endure its duration; it holds it. It does not traverse it but embraces it in a single act.
The contrast with what lives in time is immediate. Boethius states it plainly: nothing that exists in time can “embrace all the moments of its duration at once.” We never possess our whole life; we have only this slender thread of the present, “this fleeting, rapid moment,” wedged between a lost past and a future not yet grasped. To exist in time is to be perpetually lacking in oneself.
Hence a correction Boethius insists upon, against Plato and Aristotle: even if the world had no beginning and will never end, that does not make it eternal—only perpetual. To endure without end is still to move from moment to moment without ever possessing the whole. Eternity is not an infinitely extended line: it is a point that contains everything.
It is in this point that aeternitas diverges from Augustine’s distentio animi. For Augustine, the human soul measures time because it stretches, dissipates between expectation and memory; time is this inner rupture. Boethius describes the exact opposite: a life gathered, undivided, without extension. One is the scattering of a being that flows; the other, the fullness of a being that holds itself.