Whatever I wanted to leave for the ages, I would write up as a story. The best stories tend to be preserved for thousands of years. That is, they get transferred from one medium to another, from one culture to another, and so forth. Gilgamesh, for instance, contains an account of a flood that seems to have come down to us in modified form as Noah's Flood. But Gilgamesh is thousands of years old in written form and most likely was preserved in an oral form for considerable time before it was written down.
People like stories. They preserve the ones they love the most.