On the site Permaculture Principles, Australian permaculturist David Holmgren states in the introduction:

"Permaculture is a design system based on ethics and principles which can be used to establish, design, manage and improve all efforts made by individuals, households and communities towards a sustainable future."

This site explores the 'essence of permaculture' in a simple and clear way, expanding on the work of [David Holmgren], co-originator of the permaculture concept..."

A summary pamphlet in PDF format written by Holmgren entitled Essence of Permaculture is attached below for download.