An it harm none, do what thou wilt.
I used to try to follow this maxim meticulously. It made perfect sense, and fit in well with my transition from Christianity. But the more I thought and learned about my path, the more uncomfortable with this maxim I felt. At this point, I no longer think it is possible to follow, or even is a good idea.
Harming someone. How do you define this? Are you talking about physical harm to people? If so, that seems easy to follow, on the surface. But "physically" isn't specified. Neither is species - if you are attacked by a wild animal, are you supposed to let yourself die rather than harm that animal? This seems remarkably counter to nature (which is, after all, supposed to be most pagans' ruling concept), where survival of the fittest is the law. What about "tough love?" Are you supposed to let the puppy pee all over the house rather than risking "harming" him with punishment? And how many of us really hesitate to swat a biting mosquito?
And still we're restricting our scope to the animal kingdom. I often laugh when a vegetarian looks at me in scorn as I eat my steak. Is taking the life of a plant any less feeding on the death of another than eating the flesh of an animal? After all, when you talk of ecological importance - if every animal became extinct, the plants would still survive (though I will concede that those which rely on animal spoor to spread their seeds may have issues). But if all the plants became extinct, the animal kingdom wouldn't be that far behind. And yet to survive, we must minimally eat plants - which kills at least part of the plant, if not all. Clearly, not harming plants is not an option.
Then there's the mineral kingdom. I will certainly concede that most of us do not attribute sentience or consciousness to every rock, every grain of dirt or sand - but many of us do. How then to justify crushing rocks to form concrete, or quarry stone for buildings? How to justify baking clay for bricks, or mining metal? Even if we go back to stone-age technology, we must still knap flint and obsidian for hunting, chopping, and digging tools. Perhaps fallen branches sharpened by fire (from deadfall also, of course) will suffice for tools, but even then you take away that wood from those creatures that live on or in deadfall.
And to take it one step further - the very ear we breathe is full of life as well, from microbes to pollen. The bare act of breathing does violence to these things. Clearly, not physically harming something is a physical impossibility. You can argue that this is taking the maxim too far, but who draws the line? Who says "Not harming others applies this far and no farther? Certainly not Mother Nature, who nurtures animals that eat their kills alive. Clearly not She who dictates that life is supported by death. And that dictate holds true for plants and minerals as well - just watch one plant choke another to death, or listen to the rocks groan in an earthquake.
Extending harming another to include violating free will is no less ridiculous. Do you ask a man if he wants help before you knock him out of the way of an oncoming vehicle? Do you consider the free will of a pet as you housebreak it? Do you consider the free will of the corn you roast on the cob?
Plainly, the Wiccan Rede and a spirituality that is based on nature are not exactly compatible. But what would be? Survival of the fittest hardly seems like a deep spiritual truth. To me the answer is simple. You must acknowledge the prevalence of death and darkness in life, and accept it. Then try to act with respect. Very few animals kill for pleasure. Keep this in mind as you go about your day. Everything that we do is destructive in some way - without destruction, creation cannot happen. Not acknowledging this dark side to everything is nothing short of hiding from reality. And to many people, this is exactly what they want. It's a hard truth to live with. But to me, it's key to the Shadow Dance.