"The cosmos was originally all hydrogen and helium. Heavier elements were made in red giants and supernovas and then blown off to space, where they were available to subsequent generations of stars and planets. Our sun is probably a third generation star. Except for hydrogen and helium, every atom in the Earth was synthesized in other stars. The silicon in the rocks, the oxygen in the air, the carbon in our DNA, gold in our banks, the uranium in our arsenals were all made thousands of light years away, and billions of years ago. Our planet, our society, and we ourselves are built of star stuff."
— Carl Sagan