Humanity, individually and collectively, should stop dancing on the edge of a precipice! At least, I think that that is a very powerful and appropriate metaphor. Here is another, possible only since the twentieth century:
"'You'll certainly get a stiff reprimand at the very least, as close to the black hole as you've orbited.'"
-Poul Anderson, "The Sorrow Of Odin The Goth" IN Anderson, TimePatrol (Riverdale, NY, 2006), 2319, p. 377.
A black hole is an ultimate precipice.
The conclusion of this chapter reflects on the life of a Time Patrolman. The doctor wants to help Carl past his guilt and grief because:
"'You are a field agent of the Time Patrol; this is not the last mourning you will ever have reason to do.'" (p. 378)