Gasan (1275–1366) was a Japanese Soto Zen master, five generations removed from Eihei Dogen (Dogen was his teacher's teacher's teacher's teacher). Gasan once instructed his followers, "Those who speak against killing and who desire to spare the lives of all conscious beings are right. It is good to protect even animals and insects. But what about those persons who kill time, what about those who are destroying wealth, and what about those who destroy political economy? We should not overlook them. Furthermore, what of the one who preaches without enlightenment? He is killing Buddhism."
Gasan took a more expansive view on the precept of not killing than most (and gives me a strong reason to stop talking!). The late John Daido Loori also expanded upon our usual understanding of the precepts. In an interview, he once said, “Usually when people look at the Buddhist precepts, they understand them in terms of human relationships … Do not kill. Do not steal. Do not lie. Of course these are about human relationships, but what do they mean in terms of the environment?
"There is a particular kind of stealing that we do when we clear-cut forests, when topsoil is washed into rivers. There is a particular kind of killing that we do when we wipe out whole species. These precepts are taught not only as they relate to humans but also how they relate to the environment, to the ten thousand things. Not only the sentient, ‘feeling’ beings — deer, muskrat, beaver — but to the rocks, trees and river. All of it.”