If you stop to think about life philosophically, you soon run into enormous puzzles. Consider the following: every one of us is a collection of atoms that are more than the sum of its parts. The extra dimension is what we call consciousness. But consciousness is just a label. Labels don’t convey the sheer miracle of who we are and what we are: our unique capacity to feel, to think, to reason, to use language in words and songs to express ourselves and so on. Between our atoms and our “consciousness” lies a conceptual black hole – we simply do not know where our consciousness lies, let alone understand its workings. And when we die, our atoms live on, somewhere in the universe and perhaps, bits of our consciousness too. They will float around like detritus until the universe itself burns out, which is likely to be a long, long time away. In this sense, we are immortal. The poetic physicist, Alan Lightman (b. 1948) puts it this way:
Despite my belief that I am only a collection of atoms, that my awareness is passing away neuron by neuron, I am content with the illusion of consciousness. I’ll take it. And I find a pleasure in knowing that a hundred years from now, even a thousand years from now, some of my atoms will remain in this place where I now lie in my hammock. Those atoms will not know where they came from, but they will have been mine. Some of them will once have been part of the memory of my mother dancing the bossa nova. Some will once have been part of the memory of the vinegary smell of my first apartment. Some will once have been part of my hand. If I could label each of my atoms at this moment, imprint each with my Social Security number, someone could follow them for the next thousand years as they floated in air, mixed with the soil, became parts of particular plants and trees, dissolved in the ocean and then floated again to the air. Some will undoubtedly become parts of other people, particular people. Some will become parts of other lives, other memories. That might be a kind of immortality 
So if you think of life philosophically, the puzzles pile up: we are finite, yet immortal. We are atoms, yet more than atoms. Perhaps most improbable of all is the fact that we exist at all, that life exists within the billionth of a billionth of the universe that is not dark matter. Put another way, if all the matter in the universe were the Gobi desert, life on Earth is but a single grain of sand.
We are that grain of sand.
 Alan Lightman is the author of six novels, including the international best seller Einstein’s Dreams and The Diagnosis, a finalist for the National Book Award. He has taught at Harvard and at MIT, where he was the first person to receive a dual faculty appointment in science and the humanities. He is currently professor of the practice of the humanities at MIT. This quote is taken from his latest book, Probable Impossibilities: Musings on Beginnings and Endings, Pantheon, 2021.