Read "On the Immortality of the Soul" by Baruch Spinoza online for free on Textopian. Full text with search, annotations, highlights, and AI-powered reading aids.
If only we consider attentively what the Soul is, and whence its change and duration originate, then we shall easily see whether it is mortal or immortal.
Now we have said that the Soul is an Idea which is in the thinking thing, arising from the reality of a thing which exists in Nature. Whence it follows that according to the duration and change of the thing, so must also be the duration and change of the Soul. We remarked, at the same time, that the Soul can become united either with the body of which it is the Idea, or with God, without whom it can neither be, nor be known.