YES! Magazine Editor's Note: Wangari Maathai, the Kenyan activist and 2004 winner of the Nobel Peace Prize, passed away on September 25. In this essay from her book Replenishing the Earth: Spiritual Values for Healing Ourselves and the World, she describes what motivated her groundbreaking work.Wangari Maathai (1940-2011)

During my more than three decades as an environmentalist and campaigner for democratic rights, people have often asked me whether spirituality, different religious traditions, and the Bible in particular had inspired me, and influenced my activism and the work of the Green Belt Movement (GBM). Did I conceive conservation of the environment and empowerment of ordinary people as a kind of religious vocation? Were there spiritual lessons to be learned and applied to their own environmental efforts, or in their lives as a whole?

When I began this work in 1977, I wasn't motivated by my faith or by religion in general. Instead, I was thinking literally and practically about solving problems on the ground. I wanted to help rural populations, especially women, with the basic needs they described to me during seminars and workshops. They said that they needed clean drinking water, adequate and nutritious food, income, and energy for cooking and heating. So, when I was asked these questions during the early days, I'd answer that I didn't think digging holes and mobilizing communities to protect or restore the trees, forests, watersheds, soil, or habitats for wildlife that surrounded them was spiritual work.

However, I never differentiated between activities that might be called "spiritual" and those that might be termed "secular." After a few years I came to recognize that our efforts weren't only about planting trees, but were also about sowing seeds of a different sort—the ones necessary to give communities the self-confidence and self-knowledge to rediscover their authentic voice and speak out on behalf of their rights (human, environmental, civic, and political). Our task also became to expand what we call "democratic space," in which ordinary citizens could make decisions on their own behalf to benefit themselves, their community, their country, and the environment that sustains them.

In this context, I began to appreciate that there was something that inspired and sustained the GBM and those participating in its activities over the years. Many people from different communities and regions reached out to us because they wanted us to share the approach with others. I came to realize that the work of the GBM was driven by certain intangible values. These values were: love for the environment; a gratitude and respect for Earth's resources; a capacity to empower and better oneself; and a spirit of service and volunteerism. Together, these values encapsulate the intangible, subtle, nonmaterialistic aspects of the GBM as an organization. They enabled us to continue working, even through the difficult times.

Of course, I'm aware that such values are not unique to the Green Belt Movement. They are universal; they can't be touched or seen. We cannot place a monetary value on them: in effect, they are priceless. These values are not contained within certain religious traditions. Neither does one have to profess a faith in a divine being to live by them. However, they do seem to be part of the our human nature and I'm convinced that we are better people because we hold them, and that humankind is better off with them than without them. Where these values are ignored, they are replaced by vices such as selfishness, corruption, greed, and exploitation.

Through my experiences and observations, I have come to believe that the physical destruction of the earth extends to us, too. If we live in an environment that's wounded—where the water is polluted, the air is filled with soot and fumes, the food is contaminated with heavy metals and plastic residues, or the soil is practically dust—it hurts us, chipping away at our health and creating injuries at a physical, psychological, and spiritual level. In degrading the environment, therefore, we degrade ourselves.

The reverse is also true. In the process of helping the earth to heal, we help ourselves. If we see the earth bleeding from the loss of topsoil, biodiversity, or drought and desertification, and if we help reclaim or save what is lost—for instance, through regeneration of degraded forests—the planet will help us in our self-healing and indeed survival. When we can eat healthier, nonadulterated food; when we breathe clean air and drink clean water; when the soil can produce an abundance of vegetables or grains, our own sicknesses and unhealthy lifestyles become healed. The same values we employ in the service of the earth's replenishment work on us, too. We can love ourselves as we love the earth; feel grateful for who we are, even as we are grateful for the earth's bounty; better ourselves, even as we use that self-empowerment to improve the earth; offer service to ourselves, even as we practice volunteerism for the earth.

Human beings have a consciousness by which we can appreciate love, beauty, creativity, and innovation or mourn the lack thereof. To the extent that we can go beyond ourselves and ordinary biological instincts, we can experience what it means to be human and therefore different from other animals. We can appreciate the delicacy of dew or a flower in bloom, water as it runs over the pebbles or the majesty of an elephant, the fragility of the butterfly or a field of wheat or leaves blowing in the wind. Such aesthetic responses are valid in their own right, and as reactions to the natural world they can inspire in us a sense of wonder and beauty that in turn encourages a sense of the divine.

That consciousness acknowledges that while a certain tree, forest, or mountain itself may not be holy, the life-sustaining services it provides—the oxygen we breathe, the water we drink—are what make existence possible, and so deserve our respect and veneration. From this point of view, the environment becomes sacred, because to destroy what is essential to life is to destroy life itself.