It is a common expression, used chiefly in pious language, to speak of a person who is dying as going out of time into eternity.
This statement requires us, in turn, to consider the definition of “eternity” — often conceived as endless time. But this common notion of eternity quickly collapses: if you’re leaving time altogether, then you’re not in endless time, you’re in no time at all.
This expression would in fact say nothing if eternity is understood here to mean a time proceeding to infinity; for then the person would indeed never get outside time but would always progress only from one time into another. Thus what must be meant is an end of all time along with the person’s uninterrupted duration; but this duration (considering its existence as a magnitude) must be meant as a magnitude wholly incomparable with time (duratio noumenon), of which we are obviously able to form no concept (except a merely negative one).
Yet another puzzle arises: if the person’s existence “endures” the fact that he left time, how do we define “endure” — which is itself a temporal concept? We want to say that the person continues to exist after leaving time - but “continue” is a chronological notion! How can we say that the person still exists, when “still” makes no sense without reference to time?
Here we have to do (or are playing) merely with ideas created by reason itself, whose objects (if they have any) lie wholly beyond our field of vision; although they are transcendent for speculative cognition, they are not to be taken as empty, but with a practical intent they are made available to us by law-giving reason itself.
Kant reminds us here that in contemplating existence outside of time, we are at the very limit, or perhaps past the limit, of what human reason can grasp. His famous distinction between pure reason and practical reason comes into play here. On the level of pure reason, we can know little or nothing about the process of leaving time, or about exactly what it even means to leave time or be outside of time. On the level of practical reason, however, Kant informs us that we have license to follow the evidence and form hypotheses about this topic, because such working hypotheses are necessary for practical (which Kant often means moral or ethical) decisions.
A slightly different topic is, rather than an individual person leaving time, the notion that time itself ends. Again we are faced with puzzling imaginations of what this might mean. Grappling with this question in an eschatological context, Kant writes that the end of time would mean
that henceforth there shall be no alteration; for if there were still alteration in the world, then time would also exist, because alteration can take place only in time and is not thinkable without presupposing it.
Outside of time, there can be no change, for example, I cannot stand now and sit then, because there is no “now” and no “then” — presumably, I would always be both standing and sitting. Our difficulty, or inability, to even imagine or conceptually frame such things results, Kant would argue, from the fact that our minds are structured around time, or that time is the structure which our minds use to form concepts. If a man were born blind and had never seen colors, it would be difficult for him to imagine blue or green. Our minds must always structure concepts within the framework of time, and so it is difficult for us to create concepts in any other way, or to create any other kind of concept.
Now here is represented an end of all things as objects of sense - of which we cannot form any concept at all, because we will inevitably entangle ourselves in contradictions as soon as we try to take a single step beyond the sensible world into the intelligible.
Kant writes that is perhaps for the purposes of practical hypotheses that the concept of eternity (in the sense of an infinite span of time) is used; clearly, being in eternity and being outside of time are two very different things. Eternity is, however, perhaps somewhat easier to imagine, and forms a ready concept which works as well as “being outside of time” for practical purposes. This may be somewhat like our habit of sloppily blurring the distinction between weight and mass in the butcher shop: I might get a pound of pork, or a half kilogram of pork. A rude violation of physics, but for practical purposes an equivalent measure.
