This image crops up a few times in the poem, although the speaker refers to it in slightly different ways. One of the big ideas in "Thanatopsis" is that all the people in the history of the world are part of a long line, heading down into the grave. It’s all part of getting us to focus on the big picture of death, not just on our little personal fears.
- Line 71: We’ve just run through a long list of different kinds of people. Now we imagine them being "gathered" one at a time to sleep with us under the ground. A powerful, irresistible force pulls them down, no matter who or where they are.
- Line 74: Here the speaker asks us to imagine ourselves as part of an "innumerable caravan" heading toward "that mysterious realm" of death. There are a couple of things about this image that make it powerful. First, there’s that sense of infinity, that we can’t even begin to count the people who have died and will die. Second, we get a sense of motion that can’t be stopped, a marching line that moves on and on whether we like it or not. It’s all beyond our power.