I'm a bit embarrassed to be considered one of the fathers of a school of literary criticism when I didn't do much if any literary critical work myself. I liked being outside—what can I say? Nevertheless, there are a few books and ideas that made a big impression on me.
Frederic Clements and other biologists thought of an ecosystem—think of a pond or a prairie—as a super-organism. All members of an ecosystem do their own thing, but they all interact with each other at the same time. Ecosystems themselves interact this way with other ecosystems; you can think of the earth itself as one big super-organism.
Herbert Spenser, a buddy of Charles Darwin, riffed on this idea to talk about human society as a kind of super-organism, one that relies on the super-organism of the earth to stay alive. Thinking this way helps us understand our place the environment, and it helps make nature writing more personal and empathetic.
Henry David Thoreau said, "In wilderness is the salvation of the soul." I couldn't agree more.
I didn't critique Thoreau's writing or his philosophy, because I thought his ideas were right on. Like Thoreau, I think that the soul of a person is only a part of the larger soul of the earth, and I think that literature is one way that soul of the world expresses itself.
If we only express what goes on inside human heads, in cramped cities, in wars, in sordid love stories, or in oversimplified good-guy/bad-guy narratives, the world soul will eventually die. Thoreau shows us how to get outside ourselves and live as a character in a story that happens within a broader environment.
I use the example of Odysseus hanging twelve of his slave girls after his return home as a starting point to discuss ethics. This is a bizarre example, but it shows how some women in antiquity lacked basic civil rights and were nothing more than chattel.
The slave girls were Odysseus's property, so he could do whatever he wanted to with them. As societies developed, we expanded our ethics to include the rights of women as well as other races and even animals. I say we should extend these rights to the land as well. It's a natural progression, don't you think?
I recommended this book by John Muir to all my students. I loved to consider Muir's big question from this book: "What are rattlesnakes good for?" Muir's answer was that living things don't have to be good for anything in order to have the right to live. They have the right to live because they are alive.
I know I've been ripping on Captain Ahab, but if we give Moby-Dick an ecocritical reading, we see that Ahab saw no reason whatsoever for that whale to live. Whales eat legs and destroy ships, right? So they shouldn't be allowed to live, right? Wrong. Muir says that Moby Dick has every right to eat legs and destroy ships and just generally live. Life is life, and it shouldn't be taken away.