Imagine a bunch of people traveling in different directions in the snow. Rather than going directly towards their intended destination, everybody goes first to

Imagine a bunch of people traveling in different directions in the snow. Rather than going directly towards their intended destination, everybody goes first to one particular spot, where there is one pair of boot imprints. You walk toward the bootprint, step into it, step out of it, and then continue on your merry way. When lots of people do the same, you see a bunch of tracks going into one bootprint, and a bunch of tracks going out. But because everybody was careful to place their feet into the one bootprint indentation, the person following your tracks won't know which of the many forward paths you took after you stepped out.