This is from one of my favorite books, "A Severe Mercy" by Sheldon Vanauken. I find it a compelling (though not complete by any means) argument that humans were created for eternity, and not just for this world.
How strange that we cannot love time. It spoils our loveliest moments. Nothing quite comes up to expectations because of it. We alone: animals, so far as we can see, are unaware of time, untroubled. Time is their natural environment. Why do we sense that it is not ours? C. S. Lewis…asked how it was that I, as a product of a materialistic universe, was not at home there. "Do fish complain of the sea for being wet? Or if they did, would that fact itself not strongly suggest that they had not always been, or would not always be, purely aquatic creatures?" Then, if we complain of time and take such joy in the seemingly timeless moment, what does that suggest? It suggests that we have not always been or will not always be purely temporal creatures. It suggest that we were created for eternity. Not only are we harried by time, we seem unable, despite a thousand generations, even to get used to it. We are always amazed at it - how fast it goes, how slowly it goes, how much of it is gone. Where, we cry, has the time gone? We aren't adapted to it, not at home in it. If that is so, it may appear as a proof, or at least a powerful suggestion, that eternity exists and is our home.