E1D8
Definition — Part I
Latin
Per æternitatem intelligo ipsam existentiam quatenus ex sola rei æternæ definitione necessario sequi concipitur.
Explicatio: Talis enim existentia ut æterna veritas sicut rei essentia concipitur proptereaque per durationem aut tempus explicari non potest tametsi duratio principio et fine carere concipiatur.
English (Elwes 1883)
By eternity, I mean existence itself, in so far as it is conceived necessarily to follow solely from the definition of that which is eternal.
Explanation: Existence of this kind is conceived as an eternal truth, like the essence of a thing, and, therefore, cannot be explained by means of continuance or time, though continuance may be conceived without a beginning or end.
Modern English
By eternity I mean existence itself, in so far as it is conceived to follow necessarily from the definition of the eternal thing alone.
Explanation: Existence of this kind is conceived as an eternal truth, in the way the essence of a thing is conceived, and so cannot be explained by means of duration or time, even though duration can be conceived as having neither beginning nor end.