Spinoza's Ethics: I.D8: Eternity

Here Spinoza correlates "eternity" or aeternitatem with "existence itself" or ipsam existentiam. These two concepts differ in my mind. Eternity seems unchanging and abstract. In contrast, existence seems dynamic and concrete. But here, as in ID.1, Spinoza takes that which is transcendent and abstract and makes it immanent and concrete.

This connecting of the transcendent with the immanent is qualified by his use of the word "itself" or ipsam. Spinoza is laconic and for this reason, the inclusion of "itself" is significant. If  "itself" were not included, we might simply place "eternity"and "existence" on a fully equal plane. But by adding "itself", Spinoza connects "eternity" with the core or essence of "existence." Neatly, that “essence” of “existence” brings us back to the definition of “self-caused” in I.D1. Even more, it is fitting that eternity would be “self-caused.”

This connection is further qualified "existence itself" by the phrase beginning with "insofar as" or quatenus as a subset of the core or essence of existence. This part of the core of existence is "conceived of" or concipitur (a word that been addressed in the post on I.D4 implying that it is understood not sensically, but intuitively) so that only the characteristics which follow from eternal are understood. I think that his reasoning is that substance is beyond time and, in fact, creates time and its conditions. For that reason, a connection to time is to confuse what is primacy.

His explanation confirms this and is basically describing a way in which an aspect follows in a certain necessity, as in the circularity of a circle or here, the eternity of the eternal, that is the essence of a thing, which is not altered or impacted by time.

Per aeternitatem intellego ipsam existentiam quatenus ex sola rei aeternae definitione necessario sequi concipitur.

Translated as,

By eternity I understand existence itself insofar as it is conceived to logically follow from only the definition of an eternal thing.

Explicatio: Talis enim existentia ut aeterna veritas sicut rei essentia concipitur proptereaque per durationem aut tempus explicari non potest tametsi duratio principio et fine carere concipiatur.

Translated as,

For such is existence conceived as an eternal truth just as the essence of a thing and on that account cannot be explained by duration or time even if the duration is conceived to lack a beginning or an end.