Back when I heard Carl Sagan tell me I was made of starstuff when I first watched Cosmos it was a profound, world-changing statement. Today, people saying it are probably making fun of grandiose, pompous ideas. But it really still is a profound truth which bears thinking about.
On the tip of your pinky there is a carbon atom, and if you thought about it at all, you would think of it as just being part of you, of your pinky specifically. But before it was where it is, it was placed there by enzymes in a cell, and before that, it's travelled for months and years around your body, being part of many different organs and systems. It probably was part of things that got broken down and built back up hundreds of times, and moved through all parts of your body, and now it happens to be in your pinky, but that doesn't mean it will stay there.
Before it was in your body, it was part of a cow, and it went through the same dizzying series of transformations and movements within the cow's body. Before that, it was in a blade of grass, where it was built up and broken down inside various molecules countless times as it moved from place to place within the blade of grass, or even within one cell.
Before that, it was in the atmosphere, paired up with some oxygen. In this form, it probably saw much of the world; it travelled over oceans, it flew higher than jet planes, it swirled over deserts, it visited many of the continents. It was bound within clouds and then fell from them and then went back up into them, over and over.
Before that, it was in the ocean, and before that, it went a grand tour through the parts of a shark, and before that a minnow, and before that some algae, and before that, the ocean again, and before that a river, and before that, a mountain. And it probably has repeated all these cycles a thousand times, a million times. It was part of a fox, and before that a mouse, and before that an ant's egg, and before that an ant, and before that a part of an ant's hive, and before that another ant, and before that some mold, and before that, the ground.
Go far enough back and it will turn out it was part of a mountain, and before that, deep within the earth's crust. And before that, it floated free in space, amidst a cloud of dust in vacuum. Before that, it was part of an explosion as much more powerful than the biggest atom bomb as that bomb is more powerful than the breeze of a butterfly's wing. And before that, it was part of a star that is so long gone there is no longer any other trace it ever was, besides the unrecognizable parts it left.
Before that, it fell and rose for billions of years through the superhot gas of that star, up and down and up and down. And before that, it was near the center of that star, and...
And we're now back some ten billion years, two thirds of the life of the entire universe, and through that entire time, the atom of carbon has never changed. Sure, it's gained, lost, or shared electrons every few seconds for most of that ten billion years, but the protons and neutrons that make up its core are precisely the same today in your pinky as they were at that moment ten billion years ago. Through all those changes and cycles and movements they remain unchanged.
Yet one second earlier, they didn't even exist. Instead, all there was were a few atoms of helium that by sheer chance overcame million-to-one odds against and smashed into one another in a way that caused them to reform into a carbon nucleus. Before that, those helium atoms trace back a few more billion years before they, too, were formed of hydrogen atoms -- that is, protons -- the same way.
And before that... they go almost all the way back to the Big Bang. And if you could pluck one of those protons out right now, it would be essentially indistinguishable today, in the tip of your finger, from what it looked like one minute after the Big Bang, floating in an expanding curve of spacetime doing not much of anything.
That that carbon atom happens to be part of something that can understand this is the most amazing truth you will ever know. And at the same time, the carbon atom couldn't care less. It probably has another ten billion years to spend cycling through things before it will end up smashed into something else just the right way where it will become part of an atom of oxygen. Whereupon the same set of stories will start all over again.