Spinoza's Words: (of the eternalness of the mind)
Proposition XXI. The mind can only imagine anything, or remember what is past, while the body endures.
Proposition XXII. Nevertheless in (Deus sive Natura) there is necessarily an idea, which expresses the essence of this or that human body under the form of eternity.
Proposition XXIII. The human mind cannot be absolutely destroyed with the body, but there remains of it something which is eternal.
There is necessarily in (Deus sive Natura) a concept or idea, which expresses the essence of the human body, which, therefore, is necessarily something appertaining to the essence of the human mind. But we have not assigned to the human mind any duration, definable by time. Yet, as there is something, notwithstanding, which is conceived by a certain eternal necessity through the very essence of (Deus sive Natura) this something, which appertains to the essence of the mind, will necessarily be eternal.
Note.—This idea, which expresses the essence of the body under the form of eternity, is, as we have said, a certain mode of thinking, which belongs to the essence of the mind, and is necessarily eternal. Yet it is not possible that we should remember that we existed before our body, for our body can bear no trace of such existence, neither can eternity be defined in terms of time, or have any relation to time.
But, notwithstanding, we feel and know that we are eternal. For the mind feels those things that it conceives by understanding, no less than those things that it remembers. For the eyes of the mind, whereby it sees and observes things, are none other than proofs. Thus, although we do not remember that we existed before the body, yet we feel that our mind, in so far as it involves the essence of the body, under the form of eternity, is eternal, and that thus its existence cannot be defined in terms of time.
Comment:
I did not want to interrupt the flow of ideas in the previous part of the presentation with a necessarily lengthy exposition of Spinoza's difficult concept of immortality. I skipped over the three propositions above but here I will try to deal with them.
In the proof above Spinoza speaks of a certain "something" conceived thought the essence of (Deus sive Natura) that is connected to the eternalness of (Deus sive Natura) and to the mind and, consequently, makes the mind partake of eternity itself. But he says "eternity is not defined in terms of time, or have any relation to time."
If the Laws of (Deus sive Natura) are unchangeable, for Spinoza, they lie outside of time and therefore can be conceived to be eternal.The crux of the problem seems to be in the definition of the word eternal. Spinoza says it has nothing to do with time. He says in the very beginning of Part I as a definition –
VIII. 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.
But that doesn't help me much. He also says in Part V that it is of the nature of reason to conceive things under the form of eternity. Pollock says that Spinoza's idea is that things known under the form of eternity are eternal. He maintains that when Spinoza speaks of eternal life he means not a continuance in time but in the manner of existence, "not a future reward of perfection but perfection itself."
Pollock continues for eight pages (pgs.275 to 283) to try to explain Spinoza's thoughts put forward in these three propositions only to end with these words, "On the strength of these passages Spinoza has been called a mystic (not that mystic is a bad name to be called) and, while the passages in question have perplexed philosophical inquirers, they have exercised a sort of fascination for many readers."