Thanatopsis: Lines 7381 Summary Shmoop
So live, that when thy summons comes to join The innumerable caravan, which moves. If that was the end of the poem, it would be pretty depressing. Now, though, all of a sudden, Bryant switches the mood up a little. The speaker says: "So live." Enjoy the time you have. Sooner or later you will hear the call ("the summons") of death.