You're soaking in it!

This planet runs on recycling. Everything that's built gets torn down and reused - whether by rot, or erosion, or even by subduction. That's why the life-forms we see are the ones that are best at making copies of themselves, and why we can find traces of only a tiny fraction of all the creatures that have walked here. As well as being largely made of pieces of exploded stars, we are made of our predecessors. And because everything mixes so much, and the individual pieces are so very small, we carry parts of almost all of our predecessors.

Consider the air we breathe. According to Wiki Encyclopedia, our atmosphere weighs 5x10^18 kg, which means at sea level conditions it would be about 4x10^21 L. One litre contains about 2.7 x10^22 molecules. So there are about seven times as many as many molecules in a litre as there are litres in the atmosphere.

Just under 1% of it is Argon, a noble gas that is produced largely by the decay of the radioactive form of Potassium. Because it's a noble gas, it has a pretty simple cycle; it doesn't get made into trees, or react with minerals, or become part of water molecules and spend a few millenia in the ocean. It just stays there. And because our atmosphere is a dynamic place, it mixes pretty well. Argon makes the maths pretty simple; oxygen and nitrogen and all the rest do the same thing, in larger quantities and at much more variable rates.

If you take a litre of air, then, and mix it into the atmosphere, then everywhere you go on the planet, there's an Argon atom from your original litre - on average every 1.7 cubic metres (roughly speaking, your personal space). Or, for half litre (one standard breath), on average every 3.4 cubic meters (a medium-sized wardrobe).

What does that mean? Pick a famous saying - "I have a dream...", "Ein volk. Ein Reich. Ein fuhrer", "I am the way, the truth, and the life", "Veni. Vedi. Vici", "Watson, come here. I need you". Some of the air that was used to first say that is in the room with you. Some of the air that person breathed is in your lungs right now.

Heroes and villians, the inspirational and the pathetic. You're breathing the exact same air when you blow out the candles on your birthday cake.