I've designed this blog mainly with the intention recording farm progress, but I'm happy to share things about my understanding in correlation with that progress. In that spirit here's some definitions of permaculture. It apparently has over 30 defintions. Here's some that I found just now:
"The development of agricultural ecosystems intended to be sustainable and self-sufficient." (dictionary)

"A system of perennial agriculture emphasizing the use of renewable natural resources and the enrichment of local ecosystems." (dictionary)

"Permaculture uses a set of principles and practices to design sustainable human settlements." (Toby Hemenway)

"Permaculture is a sustainable design system stressing the harmonious interrelationship of humans, plants, animals and the Earth. The core of permaculture is design and the working relationships and connections between all things." (Bill Mollison)

"Permaculture is a way of life which shows us how to make the most of our resources by minimizing waste and maximizing potential. Conscious design of a lifestyle which is highly productive and does not cause environmental damage. Meeting our basic needs and still leaving the earth richer than we found it." (Graham Bell)

"Permaculture offers an understanding of how biological processes are integrated, and it deals primarily with tangibles: plants, soils, water, animal systems, wildlife, bush regeneration, biotechnology, agriculture, forestry, architecture, and society in the areas of economics, land access, bioregions and incomes tied to right livelihood. " (Rosemary Morrow)