Descartes discusses the immortality of the soul and how we may know it. See Synopsis of the Meditations in A Discourse on Methods. This was published in 1641.
Even at single point in time, one might argue that the soul exists as a fact. This is where a fact exists and exists forever or exists outside of time. Wittgenstein in Tractatus defines the world as the collection of facts.
1 The world is all that is the case.
1.1 The world is the totality of facts, not of things.
1.11 The world is determined by the facts, and by their being all the facts.
1.12 For the totality of facts determines what is the case, and also whatever is not the case.
1.13 The facts in logical space are the world.
1.2 The world divides into facts.
1.21 Each item can be the case or not the case while everything else remains the same.
A sequence in time involves a transform. Dedekind treats the natural numbers as governed by a successor function, i.e. pairs (n,n’).
Such a sequence can also stop.
However, even if it stops say at (100, 100′), each link still exists as a fact in the sense of Wittgenstein above. These Wittgenstein facts exist forever, or exist outside of time. For Wittgenstein these are what make up the world.
Descartes also discusses truths of arithmetic such as two plus three is five. Dedekind’s book was published in 1888. This is 247 years after Descartes’ book.
The Dedekind book gives us a valuable perspective on what natural numbers mean and the definition of addition and proof of its properties.