I would like to address the question of how it is possible that our species, Homo sapiens, the "knowing human", has contrived to get itself into this predicament of truly terrifying proportions. 
A growing chorus of voices has been pointing out that the roots of the ecological crisis must lie in the attitudes, values, perceptions and basic worldview that we humans of the global industrial society have come to hold. This worldview of the Industrial Age is a product of European and Euro-American culture that has spread throughout the globe with its capital accumulation approach to economic development. The apparent short-term successes of this model, and the collapse of the only alternative, communism, have blinded us to the insidious factors of social degeneration inherent in this model. They have also made us seemingly oblivious and helpless in the face of the ecological destruction taking place in almost all the planet’s major ecosystems. 

Amnesia and Domination
Several different metaphors or analogies have been proposed to explain the ecologically disastrous split, the pathological alienation, between human consciousness and the rest of the biosphere. 
One is the notion that we as a species are suffering from a kind of collective amnesia. We, as a species, have forgotten something our ancestors once knew and practiced–certain attitudes and kinds of perception, an ability to empathize and identify with non-human life, respect for the mysterious, and humility in relationship to the infinite complexities of the natural world. 
The deep ecology critique of the modernist worldview goes further. It says that humans tend to assume, with both religious and scientific rationalizations, that we as a species are superior to other species and life-forms and therefore have the right to dominate, control and use them for our own purposes as we see fit. Nature has instrumental or use value only, not intrinsic value, according to this superiority complex. It has also been referred to as human chauvinism, or species-ism–the assumption of superiority and implied right to exploit and abuse. 
The religious rationalization for this position has been the well-known set of instructions from God to Adam and Eve, in the biblical Book of Genesis: "Be fruitful and multiply, and fill the Earth, and subdue it; and have dominion over . . . all the wild beasts that move upon the Earth." (Gen. 1:28). Even though ecologically minded theologians in recent times have justly argued that "dominion" does not mean "domination-exploitation" but rather "wise stewardship or management", like a gardener tending his garden, it cannot be denied that as a matter of historical fact, domination, control and exploitation have been Western humanity’s guiding values in relationship to nature.

The Rise of Science
The exploitation and destruction of the natural environment by technological means, developed in the absence of any ecological sensibility or consideration of the rights of non-human life-forms, began in the Middle Ages, increased dramatically during the times of the scientific revolution of the sixteenth century, and then again with the industrial revolution of the eighteenth and nineteenth centuries. With the work of Galileo, Copernicus, Isaac Newton, Johannes Kepler, Francis Bacon and René Descartes came the shift away from the medieval worldview toward the mechanistic-materialistic worldview of the modern era. No longer was the Earth the center of God’s creation. Man’s role, enhanced by the already considerable successes in mastering natural processes, was to function to improve on nature, to discover her secrets by experimental and quantitative means, and to put them to use for better living conditions for humans. In short, humans were to be God’s appointed mechanics, formulating and applying the new mechanical science.
The psychological motivations and the cultural-historical situation of the founding fathers of modern science were complex and challenging. Their political struggles with the spiritual and magical conceptions of medieval hermeticism, and their evident masculine gender-bias, have been documented and analyzed by feminist scholars (Merchant, 1980; Keller, 1985). They were men of religious conviction, and I do not by any means wish to minimize their achievement, particularly in helping to free European culture from the dogmatic excesses of the medieval world. I only wish to point out two crucial aspects of this worldview transition that have generally not been appreciated.
One is that a kind of deal was struck between religion and the new science, resulting in a split worldview, a culture of two worlds. The world of the Creator, of spirit, of divinity, of transcendent realities and of moral concern, was the realm of religion, and science agreed to stay out of it. On the other hand, the world of matter and forces which could be perceived through the senses and measured and manipulated was the realm of science, and the church gave the scientists free rein to develop their value-free, purposeless, blind, yet totally deterministic and mechanistic conception of the universe. Thus the stage was set for a further and complete desacralization of the natural world, with the transcendent creator progressively marginalized, until we have the totally life-less, nonsentient, purpose-less world of the modern age, in which the technological-industrial destruction of the environment is accepted and ignored.
A second aspect of the fifteenth/sixteenth century paradigm transition is that the development of the new mechanistic-materialistic worldview occurred synchronistically (that is, not coincidentally) with the birth of Renaissance humanism, the Protestant reformations, and the first explorations of the Americas. Each of these movements, unintentionally and unconsciously, further deepened the split between human consciousness and the natural world. Renaissance humanism, with the rediscovery of the culture of antiquity, celebrated the intrinsic worth of the human being and gave a much needed boost to Western humanity’s self-esteem, burdened as it was with a thousand years of indoctrination about Original Sin. But the early Italian humanists, like Marcilio Ficino and Pico della Mirandola, surely could not foresee the subtle beginnings of the humanist arrogance that was to have such devastating consequences later.
The Protestant reformation, with its emphasis on the individual’s direct access to spiritual and moral guidance from scripture, attacked the exaggerated idolatry of medieval Catholicism. But in their zeal the Protestant reformers and puritans contributed to the elimination of the last vestiges of pre-Christian European paganism, thereby further deepening the alienation of the urban populations from the psychic renewal found in a spiritual perception of the natural world.
A third movement which changed the world in the fifteenth/sixteenth centuries was the exploration of the Americas. This initiated a period in which first the Spanish and Portuguese and later the English, French and Dutch colonists-imperialists were able to extract and ship to Europe unbelievable quantities of gold, silver, foodstuffs, spices, drugs, and other raw materials, providing the fuel for the explosive growth of capital accumulation (Weatherford, 1988). This laid the foundation for the growth to world-wide dominance of the Euro-American capitalist-industrial economies, continuing to this day to ravage the biosphere with ever-increasing efficiency and intensity.

The Spiritual Self and the Natural Self
Thus, for a complex variety of social and historical causes, a core feature of the European psyche is a dissociative split between spirit and nature. We have a deeply ingrained belief that our spiritual life, our spiritual practices, must tend in the opposite direction from our nature. Spirit, we imagine, rises upward, into transcendent realms, whereas nature, which includes bodily sensations and feelings, sinks or draws us downward. In some versions of this core image, the contrast between the two realms or tendencies is even sharper–not only separation, but opposition. In the Christian, especially Protestant, version of this myth, we feel we have to overcome our "lower" animal instincts and passions, to conquer the body, in order to be spiritual and attain to "heaven", or "enlightenment".

In the modern psychological, Freudian version, the conflict is between the human ego consciousness, which has to struggle against the unconscious body-based, animal id in order to attain consciousness and truly human culture. Our conflicted relationship with the natural, what Freud called Das Unbehagen in der Kultur, the discontent of culture, was for him the price we had to pay for the possibility of civilization.

The similarity of the two formulations lies in this dualism; we could say that throughout the history of Western consciousness there has been a conception of two selves–a natural self, which is earthy and "wild", and tends downward, and a spiritual or mental self, which is airy and ethereal, and tends upward.
Perhaps its most vivid formulation is by the eighteenth century German poet-philosopher Goethe, who formulated this core dualistic image in a famous passage in his drama Faust. The story of Faust, with his restless and ruthless quest for knowledge as personal power, strikes us as somehow a mythic key to the European psyche. 

It does not take much imagination to see how the consequences of this distorted perception have been played out with the spread of European civilization around the globe. And it is a distorted, counter-factual image: We human beings are not, in fact, separate, or above nature. We are part of nature–we are in the Earth, not on it. We are like the cells in the body of the vast living organism that is planet Earth. The kind of population pressures and ecosystem destruction that we humans are now wreaking upon the body of Earth are exactly analogous to the excessive multiplication of cells and systemic malignancy that we recognize in medicine as a cancerous tumor. Humans have become a plague upon the Earth.

Overcoming the Consequences of the Human/Nature Split
The difficulty we might have in extracting ourselves from this oppositional dualism between the spiritual and the natural can be alleviated somewhat when we compare this conception to the worldview of the indigenous inhabitants of North and South America, or indeed, primal, shamanistic cultures all over the world. For these people, spirituality is not separate or above nature–the spiritual is the natural.Spiritual practice consists in communing with the living intelligences, called "spirits", perceived to be indwelling in nature, with conscious respect and reverence. Methods of heightening consciousness to bring about such communion include wilderness vision quests, sweat-lodge and other healing ceremonies involving singing, trance states induced through the use of hallucinogenic plants, postures, dancing, drumming, fasting and other practices. This is the worldview, known to anthropologists as "animism", which sees all natural forms and life-forms–including animals, plants, rocks, forests, rivers, mountains, fields, seas, winds, as well as sun, moon, stars, and the total cosmos–as pervaded by and interconnected with spiritual energy and intelligence. In theological language, such a view is known as immanentism, or panentheism –that Divinity, the creative spiritual forces, exist within, and pervade throughout, everything.

We would expect that societies with such an animistic, shamanistic, pantheistic worldview would have a very different, more respectful and less destructive relationship with their natural environment. And indeed, although pre-conquest Native Americans intervened in sometimes drastic ways with their environment, there is no evidence that in the tens of thousands of years of habitation of the American continent, they ever achieved anything even close to the kinds of massive destruction that have occurred in the past 500 years. Ecologists in all parts of the world who have been searching for ways to formulate ecologically sustainable ways of development have increasingly come to the realization that the indigenous peoples of the Third and Fourth World, with their so-called "primitive" animistic and shamanistic beliefs, have in fact been practicing the kinds of sustainable lifestyles that we are now trying to develop (Mander, 1991). Indeed, how could it be otherwise? An ecological adaptation has to be sustainable for it to have survived. The primal cultures surviving today far exceed our Western civilization in longevity.

The situation becomes even more hopeful, and our chances of overcoming the consequences of the European humanist superiority complex are even better, when we realize that not only have other cultures the world over not had this division, but that our own pre-scientific and pre-Christian ancestors also did not have it. The religion and worldview of the Celtic, Germanic, Baltic, and Slavic peoples who inhabited Europe prior to the Christian era were animistic and shamanistic. Their gods and goddesses were perceived and worshipped in forest groves and sacred springs, on mountain tops and in great stone circles. In addition to gods and goddesses, there were other classes of beings associated with nature who were not human but certainly equal if not superior to humans and deserving of respect, such as giants and dwarfs, elves and trolls, fairies, leprechauns, gnomes, satyrs, nymphs and mermaids. These deities and beings could be communed with by anyone who was willing to practice the methods taught by the shamans and their successors, the witches–the wise women of the woods–using magical plants and stones, chants and incantations, dances and rituals.
This is the nature religion that was eliminated by Christian monotheism during the first few centuries of our era. The monotheistic religions devoted considerable energy to eliminating the competition, as it were, and thereby denied the creative spiritual energies inherent in nature that the ancients had worshipped from the earliest times.
The direct communion with divine spirit, as taught and practiced by the Christian Gnostic sects, who held rituals which ordinary men or women could conduct, was banned by the Church as blasphemous. Gnosticism was violently and completely suppressed in the early centuries, so that even the Gnostic texts were lost, until they were re-discovered in Nag Hammadi, in the 1950s. In the eighth century, the Frankish emperor Charlemagne, in an attempt to forcibly convert the Saxons, caused to have cut down the Irminsul, a great ash tree that represented the central holy World Tree of the Germanic people. One can appreciate the magnitude and impact of this if one were to imagine the desecration or destruction of St. Peter’s in Rome, or the Kaaba in Mecca, or the Temple in Jerusalem.
When, starting in the twelfth century, the Church began to be concerned again about the numbers of followers who were joining reform movements like the Cathars in Provence, it launched the internal crusades and inquisitions against those it suspected and accused of heresy, including the Cathars and the Knights Templar. Anti-semitism also increased again, as the Spanish monarchy forced the Jews out of Spain in the same year that Columbus sailed for America. Finally, in the fourteenth century, the Church turned its full inquisitorial fury against the pagan witches, who were branded as "being in league with the Devil"–and therefore heretical and punishable by being burned to death.
No one knows to this day how many "witches" were killed: Estimates range from 2 to 9 million. It seems clear that the vast majority were women, many of them simple country women, some of whom were maintaining the ancient herbal knowledge, especially as it related to midwifery, contraception and abortion. 

Remembering Our Ancestors
To summarize: I have suggested that at the core of the psychic alienation of Western humanity from the natural world, with its disastrous consequences of global ecological destruction, is a humanist superiority complex that is a deeply rooted feature of the Western psyche. For a complex variety of historical reasons, Europeans and Americans have come to experience spirituality and nature as separate or opposed. "Two souls, alas, dwell in my breast . . . ." 
It was not always so. But for the last 2,000 years, under the influence of Judeo-Christian transcendental monotheism, we have become further and further removed from the kind of direct awareness of the spiritual presences in nature that our pagan ancestors enjoyed. For the last 500 years, as the worldview of medieval Christianity gave way to the mechanistic-materialistic worldview of modern science, the alienation from the Earth has become even more profound. Humanity in the modern era confronted nature as an alien and terrifying world, without even any of the other-worldly solace that religion had provided. In the modern atheistic, materialistic worldview, there is no spiritual being anywhere, either in this life or after death, either within nature or above it. Nature, seen as consisting of inert, random, machine-like processes, had to be conquered, subdued, controlled and dominated–and a phenomenal technology has developed to do just that.
In pointing to the role of mechanistic science and industrial technology in aggravating our alienation from the Earth, I do not suggest an impossible, "neo-Luddite" return to a pre-industrial era. I do suggest that it is possible to recall certain values that we have lost, and that it is desirable to examine the value systems with which we develop and apply technology. Economist-philosophers such as E. F. Schumacher, Ivan Illich and others have suggested "small-scale" and "appropriate" technologies. Instead of being used to feed runaway cycles of exploitation and addictive consumerism ("producing more and more goods for more and more people"), technology needs to be re-directed toward the preservation and restoration of damaged eco-systems, which can sustainably support all forms of life, including–but not limited to–the human. Models and designs for this kind of ecologically sensitive technology exist: We only have to muster the political will to choose them.
Similarly, in pointing to the role of transcendental monotheism and the Christian anti-pagan bias in the severing of our spiritual connection to the natural world, I do not imply that we must all become pagans and deny 2,000 years of Christianity, plus Judaism and Islam. These traditions have become an indelible part of our psychic constitution. I do believe it is possible for Christians, Jews and Muslims to re-connect with the nature religion of their ancestors, and that when they do so a tremendous spiritual revitalization can take place, in which the natural world and the divine world are recognized as one and the same. I see this as a kind of remembering, like Odin the shaman-god drinking from the well of remembrance, situated at the root of the great world tree–from which he gained ancestral and evolutionary knowledge of the origins of things, and the value of such remembering for the present and the future.

Mystics and Artists
The dualistic split which I am claiming is characteristic of the European and American psyches applies to the dominant collective consciousness. There have been exceptional individual mystics and artists who have articulated quite a different view. Here are three examples: