Permaculture seems to be all about self-sustaining resource systems that operate without the help of a person and can support human life. Its permanent because it operates on its own without the help of humans, kinda like things were before agriculture and domestication when people lived off wild ecosystems that were not domesticated.
I think most people would be happy if they can manage a system that isn't degrading the environment. Considering we expect our systems to support us, it seems reasonable to me to return some of our own labor to support the system. What ever system someone develops, so long as it doesn't deplete our resources faster than they replenish, it can probably meet someone's definition of permaculture. It's when we steadily deplete and overuse what can't be replaced that we destroy all possibility of permanence.
Benton, I don't see the definition of permaculture being a system without human input. It's not a self-operating Garden of Eden. Instead, I see it as a permanently producing agricultural system that could go on for hundreds or thousands of years without degrading. This would imply that finite resources, such as oil derived products, would not be part of the system.
It's never too late to start! I retired to homestead on the slopes of Mauna Loa, an active volcano. I relate snippets of my endeavor on my blog : www.kaufarmer.blogspot.com