Close your eyes and slowly inhale. Hold it to a count of six, then breathe out gradually.
It's often said that each time you do that, you are likely to breathe in a molecule from Julius Caesar's dying breath.
At first sight this is surprising.
But there are an enormous number of molecules in a breath of air. If the molecules in Caesar's last gasp are shared out evenly across the whole of the earth's atmosphere—plausible after 2000 years—then on average the air we inhale with each new breath (about 500 ml) will include one of those molecules.
Julius Caesar could just as well be any person that has ever lived.
Or the last mammoth.