Explication of "Barbarians" By Mary Ruefle

This poem sets up a scene of cows laying in a field and in the trees sleeping. I took this poem to mean that the cows were exposing themselves to danger but had no idea of it. "As though sleep were an idea for which they were willing to die" means that these cows were maybe being stalked by some predator. The predator is waiting for the cows to go to sleep so that it can make its move and that is why sleeping is an invitation to die.