Along with philosophers and psychologists from Plato through Maslow, Lee believes that humans progress through hierarchical stages of biological and moral development. Humans, according to the author, also live at different levels of being and participate in biological, social, rational, cultural, and individual activities. At each developmental stage and in each sphere of activity, people have different needs. A hierarchy of species and individual needs provides an objective basis for ethics. This ethical system extends beyond humanity and embraces environmental ethics as well. The ethical goal of humanity, says Lee, is to create a sound world order that meets human and environmental needs at all levels. Lee begins this study by providing an anthropocentric model for his ethical theory. He expands this model to include hierarchies within the natural world and he integrates human and environmental ethical concerns. He then examines the shortcomings of both capitalism and Marxism in meeting environmental and human needs, and he concludes that a sound world order must be based on political and economic systems that universally address all needs at all levels. Philosophers, psychologists, and all those interested in the human condition will find this work an illuminating synthesis of enduring issues.