Nature is not utterly debased, according to Steiner. The natural world is infused by the spiritual world; indeed, all of physical reality is just a condensation of spiritual reality. In this sense, nature deserves our respect, even our reverence. Moreover, with the Crucifixion, Christ's blood — his essence, as it were — flowed into the Earth. So, Steiner taught, the natural realm on the Earth has a sort of holiness, and for this reason Anthroposophists are often advocates of "green" beliefs, promoting conservation, organic gardening, and ecological sensitivity.
But the other pole, the aversion to nature, still stands tall in Anthropological doctrines. Nature is not wholly evil, but elements of evil run through it. It is the abode of “elemental beings” or “nature spirits,” lowly and generally amoral beings. Some of these entities have been given names such as “goblins.” Yes, Steiner taught that such mythical creatures as goblins are real. They are more or less antithetical to humans, although their actions can benefit us — they represent stages of existence that are beneath us, yet they may serve us. Animals also represent such low stages — they are beneath us, yet they have their uses.
Let’s start by hearing about the animals, since they actually exist. During an early period of our evolution, according to Steiner, man shed the various animals out of himself, one by one. Man did not evolve upward from the animals; rather, animals evolved downward from man. Humans existed before any of the animals came into existence. Then, as humans developed, we cast aside various lowly portions of ourselves. These became the animals.
“The higher animals did not yet exist ... Man was there, but in quite a different form ... Afterward, man evolved higher, and left behind him the fish-form which had been contained within him ... Again man evolved higher, and separated the birds from himself. Next the reptiles and amphibians came out of man ... Later still, man put the mammals out from himself....” 
The main point to note in Steiner’s absurd account is that animals are beneath us; we had to rid ourselves of them. They represent inferior characteristics we had to shed on our evolutionary ascent — they are the debris we left behind. Unless we continue to reject them, we will slip backwards spiritually.
Nature spirits may represent another form of debris. Inferior humans who fail to climb the evolutionary ladder “fall out of evolution” , after which they deteriorate to subhuman status in the form of nature spirits. This fate entails losing the ability to reincarnate, which means losing the capacity to make progress from life to life.
“Such souls lose the possibility of incarnation and find no other opportunity ... [T]here are no more bodies bad enough [to house them] ... Beings that stay behind at such stages appear in a later epoch as subordinate nature spirits.” 
Steiner said that losing the ability to reincarnate makes you a merely “natural” being.
“Quite a number of people have been born [who]...are not reincarnated, but are human forms filled with a sort of natural demon. There a quite a large number of older people going around who are actually not human beings, but are only natural.” 
To be “natural,” in Steiner’s teachings, is to be inferior and wicked.
Goblins, specters, undines, phantoms, and so forth, are overlapping examples of nature spirits. The four main types of nature spirits are gnomes (aka goblins), sylphs, undines, and fire spirits (aka "salamanders".) These are higher than the "subordinate" nature spirits that wicked people may become, but they are nonetheless beneath us. One handy term to cover them (not quite accurate, but handy) is "fairies." As a rule, nature spirits are not our friends. If they are not quite immoral, they are often amoral. Concerning goblins, for instance, Steiner said:
“There are beings that can be seen with clairvoyant vision at many spots in the depths of the earth ... Many names have been given to them, such as goblins, gnomes and so forth ... What one calls moral responsibility in man is entirely lacking in them ... Their nature prompts them to play all sorts of tricks on man.... ” 
They belong to a different “world” from ours — they are part of nature in a way we are not.
“Gnomes are...unable to grasp how there can be anything but an ineffectual relationship with our world.” 
Other nature spirits may have better intentions, at least sometimes, but don't trust any of them without strong assurances.
Nature spirits can be detected by peering through seams in the natural world, Steiner claimed. For this purpose, "occult vision" — that is, clairvoyance — must be employed.
"[O]ccult vision [may attain] an impression of other beings standing immediately behind the veil of nature ... This is especially the case if we devote ourselves to the peculiar play of a body of water tossing in a waterfall and giving clouds of spray, if we yield ourselves to the forming and dissolving of mist and to watery vapour....” 
Rationally, we should say that anyone who semi-sees “fairies” a swirl of mists is experiencing an optical illusion. But Steiner, the opponent of rationality, accepted false impressions as truth. He wanted to pierce “the veil of nature” — he taught that nature is a deceptive screen that we need to get past.
The four main types of nature spirits — the four forms of fairies — can seem almost charming, and their representations in Waldorf classrooms can exert a kind of charm. But Steiner described other elemental beings, some of which are distinctly nastier than goblins. Let’s look at these, then circle back to consider the basic four. The nastiest group consists of phantoms, specters, and demons, and they literally represent wrongdoing. Phantoms, the mildest of the lot, are wraiths that come to Earth through the physical bodies of wrongdoers. They are
“beings which have been created in the physical body through the effect of lying and slander ... Such beings...now flit and whirr about in our world and belong to a class that we call ‘phantoms.’ They form a certain group of elemental beings related to our physical body and invisible to physical sight.” 
Specters embody transgressions associated with our “etheric” bodies. Steiner said that we have three nonphysical bodies in addition to the physical body — the etheric body, the astral body, and the “I.” Lowly specters are comfortable in our lowest incorporeal bodies, our etheric bodies.
“All that leads to want of harmony, all that makes for bad adjustments between people...is continued into the etheric body.” 
Wrongs committed by humans (inharmonious behavior, bad relationships) cause detritus to drop from the spiritual worlds and manifest in our environment:
“The accumulation in the etheric body caused through these [wicked] experiences of the soul...brings about detachments from the beings working in the spiritual worlds and these likewise are now to be found in our environment — they are the ‘specters’ or ‘ghosts.’” 
Don’t be misled by the idea that specters and ghosts come from the spiritual worlds — they are not truly spiritual beings. Steiner sometimes called nature spirits “elemental beings” or "elementals" precisely in order to stress their lack of spirit:
“To call them elemental spirits shows the greatest possible ineptitude, for it is just [i.e., exactly] spirit that they do not possess. It is better to call them elemental beings....” 
The worst nature spirits are associated with our “astral” bodies. Higher than etheric bodies, our astral bodies journey into spiritual worlds every night when we sleep. Evildoing can cause an astral body to pick up wicked invisible hitchhikers or “enclosures” during the night. These wicked spirits, which Steiner identified as demons, then ride to Earth tucked inside the astral body.
“In all that works [evilly] from soul to soul in our world, from the giving of bad advice to all those methods which people employ in order to overwhelm others...[this] is expressed in the night in the astral body. The astral body gets these ‘enclosures’ and thereby beings are detached from other worlds and whirr through our world again as elemental beings. They belong to the class of demons.” 
Nature spirits can sometimes be beneficial to us, enabling us to develop and evolve above them. Indeed, when nature spirits behave themselves, they may fulfill the intentions of the gods, assisting us as the gods intend. Steiner placed the four basic types of nature spirits in the soil, air, water, and fire: goblins in the ground, sylphs in the atmosphere, undines in liquid water, and "salamanders" in flames. In giving form to the "four elements," nature spirits lay a sort of foundation for our lives on Earth. But the hostility and mischievousness of naughty nature spirits cause troubles.
"Take the gnomes and undines: they are, so to say, in the world which borders on human consciousness; they are already beyond the threshold. Ordinary consciousness is protected from seeing these beings, for the fact is that these beings are not all benevolent ... [I]n the moment when man breaks through into the world wherein they live and are active, he finds there not only the well-disposed beings but the malevolent ones as well ... The main difference between the ill-disposed beings and the well-disposed is that the latter are always drawn more to the plant and mineral kingdoms, whereas the ill-disposed are drawn to the animal and human kingdoms ... Now someone might say: Why then are these malevolent gnome and undine-beings there, if they engender parasites? Well, if they were not there, man would never be able to develop within himself the force to evolve the structure of his brain." 
According to Steiner, most things can be turned to good account, even the actions of malevolent nature spirits. But their malevolence is real, and we must tread cautiously.
The benefits we receive from nature spirits are not easy to describe (and not worth worrying about, since these doctrines are nonsense). Trying to explain, Steiner discussed our "auras," if you can believe it:
"Here on earth, a person's aura carries a kind of remnant of the things he received when he had ascended to the spiritual world [in sleep or death]. Having left behind the realms of wisdom, of beauty, of truth [spiritual realms we exit when descending to Earth again], mankind must enter the mineral, plant and animal kingdoms [i.e., nature] ... The person who does not give in to his animal instincts is not necessarily wise. The wise human being — wise in the sense implied by strength of heart — is the one who possesses moral ideas [animal instincts are lowly, sometimes sexual: earthy; wisdom is supernatural] ... [O]ur materialistic age is distinguished by the way it so thoroughly involves the sphere of sexuality in artistic considerations — a piece of mischief for which our age is responsible ... [I]t is our physical body that connects us with the realm of physical becoming, [and] our brain connects us with certain elemental beings...the elemental beings of the myths and sagas. There they are called elves, fairies, and so on.” 
Here is one of the most affirmative statements Steiner made about nature beings. See how it strikes you.
“The predecessors of our Earth-gnomes, the Moon-gnomes, gathered together their Moon-experiences and from them fashioned this structure, this firm structure of the solid fabric of the Earth, so that our solid Earth-structure actually arose from the experiences of the gnomes of the old Moon ... Now let us pass over from the gnomes to the undines, the water-beings ... These beings have not the need for life that human beings have ... [They] have rather a need for death ... They only feel their life to be truly theirs when they die ... And now let us proceed to the sylphs. In the course of the year we find the dying birds ... Dying birds possess spiritualized substance ... [T]hey desire to give this spiritualized substance over to the higher worlds ... But here an intermediary is needed. And these intermediaries are the sylphs ... And when we pass over to the fire-beings [i.e., salamanders], only think how the dust on the butterfly's wings seems to dissolve into nothing with the death of the butterfly ... When in the course of the year the butterfly-world approaches its end, all this becomes glittering and shimmering ... [I]nto this glittering and shimmering the fire-beings pour themselves; they absorb it.” 
Some of Steiner's language and concepts may seem attractive, but his essential attitude toward nature was, at best, ambivalent. He found some value in the natural world — but he also found much that he considered lowly, vile, even evil. He wanted to get past nature, moving through the "veil" toward "higher" worlds. The effort to do so may or may not be advisable — such worlds may or may not exist.
If trying to get past nature means detaching ourselves from reality, then Steiner's advice was surely perilous. Children can be educated to live in a world of Moon-gnomes, suicidal sylphs, and other imagined apparitions involved with death, or they can be raised to live and thrive in the real world, the one described in science and, perhaps, mainstream religions. Choosing to go with Steiner almost certainly means choosing an alienating cult — alienating from reality, from ourselves, and from truth.
Nature is deceptive — within it lurk demonic snares, which may cause you to use your intelligence too much. Or so Steiner said. The natural world consists of matter, which is the antithesis of spirit (although it is condensed spirit — don't expect complete logical consistency from Steiner). The snares of nature have been placed in our path by our spiritual foes, who want to trip us up with illusion.
“I must emphasize this again and again, that the saying ‘the world is Maya’ is so vitally important." 
The greatest liar, the author of so many illusions that await us in the world of matter, is the devil Ahriman.
“Ahriman infused into human observation something like a dark smoke cloud that prevents penetration to the spiritual. Through Ahriman's agency man is enmeshed in lies, in maya, in illusion.“ 
The minions of Ahriman hide just below the surface of the Earth, and they strive to create a race of subhumans residing within the elements.
“Were [the minions of Ahriman] to be successful, man would become extremely clever in the material realm — incredibly clever and intelligent. They cannot achieve their end directly, but they aim at doing so indirectly. And their efforts, which have actually been going on for thousands of years, have in fact succeeded in producing a whole race of sub-human beings. Their method is as follows. [paragraph break] Suppose a man has strong and rude instincts. These beings will clutch at his instinctive nature and seize hold of it. The man then falls victim to the Ahrimanic powers. He is completely given up to his passions and leads a wild and dissolute life. When a man has in this way become a prey, during his earthly life, to the Ahrimanic powers, then these powers will be able to hold on to his instinctive nature and tear it out of him after death. There exists already on the Earth a whole population of beings who have arisen in this way. They are there, in the elements of earth and water, a sub-human race.” 
All in all, nature is a tricky place. Respect it. But fear it. And leave it behind ASAP.
— Roger Rawlings
You will not find complete consistency in Steiner's teachings. The degree to which nature is corrupt, depraved, or evil changes from book to book, lecture to lecture. But the overall notion is plain enough: The spirit realm (or at least the part of it inhabited by the good gods) is far better than the lowly, material, dead or at least very sick physical realm.
Yet there is good in nature, or in parts of it, anyway. Here's the bright side:
“We see nature around us, and we see also that man enters into his physical existence through the forces of this same nature. We know through our study of Spiritual Science [i.e., Anthroposophy] that we do not rightly regard nature if we only pay attention to its external physical features. We know that divine forces permeate it and we only become aware of our origin from nature in the true sense of the word when we perceive this divine element that weaves and works within it. In this we perceive the Father principle of nature. All that permeates nature as the divine is the Father principle in the sense of the old religions and also in the sense of a rightly understood Christianity — whether it be the flowers of the field that we observe, and how they grow, or the roll of the thunder and the flash of the lightning; or whether we watch the sun in its path across the heavens or gaze upon the shining stars; or whether again we listen to the brooks and the streams rushing along — when we become aware of what is revealed so mysteriously in this external revelation of nature as the origin of all ‘becoming,’ then we are at the same time aware of what places us as men within this world through the mystery of physical birth.” — Rudolf Steiner, THE SEARCH FOR THE NEW ISIS, DIVINE SOPHIA (Mercury Press, 1983), lecture 1, GA 202.
But do not expect complete consistency in Steiner's teachings.
“[T]here are entities in this next-door world...which could only be made known to human beings under certain conditions. They have a specific function in the whole universe and especially also in human evolution.
“...Today I want to talk to you about one class of such entities, the class whose function in the great scheme of things is connected with human birth and death ... If one were to speak of them, and of the whole way in which these elemental spirits [sic] live, one would be speaking of something that would seem like red-hot coals to people.
“...[T]he divine spirits who guide world destinies have to use elemental spirits who actually are the enemies of everything human beings seek and desire for their welfare and well-being here in the physical world.
“...[T]he gods always rule for a time within a particular sphere of elemental spirits and then human beings enter into this same sphere and use the elemental spirits. In earlier times, the elemental spirits of birth and death essentially served the divine spirits who guided the world; since our day — and this has been going on for some time now — the elemental spirits of birth and death are serving technology, industry and human commerce.
“...[T]hese elemental spirits are the enemies of human welfare and want to destroy it. We have to see things straight and not have any illusions concerning the radical nature of this. Civilization must progress in the fields of technology, industry and commerce. But by its very nature such a civilization cannot serve the well-being of humanity in the physical world; it can only prove destructive to the human weal.
“ ...The elemental spirits of birth and death are, of course, messengers of Ahriman. The iron necessity of world evolution forces the gods to use Ahriman's messengers to control birth and death. When they ask the elemental spirits to act on their behalf they do not allow the powers of these messengers to enter the physical world. But as civilization goes into its decline, from the fifth post-Atlantean period [i.e., the fifth age since Atlantis sank] onwards, this element has to come in again, so that catastrophe may be brought about.” — Rudolf Steiner, THE FALL OF THE SPIRITS OF DARKNESS (Rudolf Steiner Press, 1993), lecture 4, GA 177.
The natural world, the Earthly sphere, the physical world — this realm might have been better except for a recent event. The Archangel Michael fought a war in Heaven, as it were, and cast his defeated enemies down to the Earth.
“Events in which humanity is now caught up...are more significant than is often realized today. I have sought to show that momentous occurrences in the spiritual world form the background to these events. I have also spoken of the profoundly significant battle which took place in the spiritual regions of the world [i.e., the cosmos: the "spiritual worlds"] between the early 1840s and the autumn of 1879. This was one of the battles which occur repeatedly in world and human evolution and are customarily represented by the image of Michael or St. George fighting the dragon. Michael won one such victory over the dragon on behalf of the spiritual worlds in 1879. At that time the spirits of darkness who worked against the Michaelic impulses were cast down from the spiritual realm into the human realm. As I said, from that time onwards they have been active in the feeling, will and mind impulses of human beings. Present-day events can therefore only be understood if one turns the inner eye to the spiritual powers which are now moving among us.” — Rudolf Steiner, THE FALL OF THE SPIRITS OF DARKNESS, lecture 13. [For more on this, see “Michael".]
The Earthly realm, and in particular the human portion of the Earthly realm, is haunted by demonic powers cast down from on high. We must hope that any beneficent spirits moving among us will assist us against the spirits of darkness present in our environs. Sadly, many of the spirits moving around and among us now are our foes.