We are able to recognize the life world behind physical nature when we begin to have a moral perception of the world lying around us.

Spiritual science does not merely signify the acquisition of knowledge; it signifies most preeminently an education, a self-education of our souls. We make ourselves different; we have other interests. When one imbues oneself with spiritual science, the habits of attention for this or that subject that one had developed in previous years alter. What was once of interest is of interest no longer; what was of no interest previously now begins to be interesting in the highest degree.
 I am speaking to those who have, to some extent, accepted spiritual science. Therefore I may take it for granted that you know that immediately behind what meets us externally as human beings—behind what we see with our eyes, touch with our hands, and grasp with our understanding in ordinary human anatomy or physiology, behind what we call the physical body—we recognize the first supersensible human principle. This supersensible principle of the human being we call the etheric body, or life body. […]
 We can do something similar with regard to the nature around us. Just as we can investigate a human being to see whether there is not something more than the physical body and then find the etheric body, so, too, we can look at external nature in her colors, forms, sounds, and kingdoms—in the mineral, plant, animal, and human kingdoms, insofar as these meet us physically. We discover that just as behind the human physical body there is a life body, so there is a sort of etheric body, or life body, behind the whole of physical nature…
 
We are more and more able to recognize the etheric world, or life world, behind physical nature when we begin to have a moral perception of the world lying around us. What is meant by perceiving the whole world morally? What does this imply? First of all, looking away from the Earth, if we direct our gaze into the ranges of cosmic space, we are met by the blue sky. Suppose we do this on a day in which no cloud, not even the faintest silver white cloudlet, breaks the azure space of heaven. We look upward into this blue heaven spread out above us; it does not matter whether we recognize it in the physical sense as something real or not. The point is the impression that this wide stretch of the blue heavens makes upon us ^1)↓.
 Suppose that we can yield ourselves up to this blue of the sky and that we do this with intensity for a long, long time. Imagine that we can do this in such a way that we forget everything else that we know in life and all that is around us. Suppose that we are able for one moment to forget all external impressions, all memories, all cares and troubles of life and that we can give ourselves completely to the single impression of the blue heavens. What I am now saying to you can be experienced by every human soul if only the soul will fulfill these necessary conditions; what I am telling you can be a common human experience. Suppose a human soul gazes in this way at nothing but the blue of the sky. A certain moment then comes, a moment in which the blue sky ceases to be blue, in which we no longer see anything that can in human language be called blue. If at that moment, when the blue ceases to be blue to us, we turn our attention to our own souls, we will notice quite a special mood within it. The blue disappears, and an infinity arises before us; in this infinity we experience a quite definite mood in our souls. A quite distinct feeling, a quite definite perception, pours itself into the emptiness that arises where the blue was before. If we would give a name to this soul perception, to what would soar out into infinite distances, there is only one word for it: it is a devout feeling, a feeling of pious devotion to infinity. All the religious feelings in the evolution of humanity have fundamentally a nuance that contains what I have here called pious devotion. The impression has called up a religious feeling, a moral perception. When within our souls the blue has disappeared, a moral perception of the external world springs to life.
 Let us reflect upon another feeling by means of which we can attune ourselves in another way in moral harmony with external nature. When the trees are bursting into leaf and the meadows are filled with green, let us fix our gaze upon the green that in the most varied manner covers the Earth or meets us in the trees; again, we will do this in such a way as to forget all the external impressions that can affect our souls and simply devote ourselves to what in external nature meets us as green. If once more we can yield ourselves to what springs forth as the reality of green, we can carry this so far that the green disappears for us in the same way that previously the blue as blue disappeared. Here, again, we cannot say, “A color is spread out before our sight.” Instead (and I remark expressly that I am telling you of things that each one of us can experience for ourselves if the requisite conditions are fulfilled), the soul has a peculiar feeling that can be articulated thus: “Now I understand what I experience when I think creatively, when a thought springs up in me, when an idea strikes me. I understand this now for the first time. I can learn this only from the bursting forth of the green all around me. I begin to understand the inmost parts of my soul through external nature when the outer natural impression has disappeared, and, in its place, a moral impression is left. The green of the plant tells me how I ought to feel within myself when my soul is blessed with the power to think thoughts, to cherish ideas.” Once more an external impression of nature is transmuted into a moral feeling.
 Or we may look at a wide stretch of white snow. In the same way as the blue of the sky and the green of Earth’s robe of vegetation, so, too, can the white of the snow set free within us a moral feeling for all that we call the phenomena of matter in the world. If, in contemplation of the white snow mantle, we can forget everything else and experience the whiteness and then allow it to disappear, we obtain an understanding of that which fills the Earth as substance, as matter. We feel matter living and weaving in the world. Just as one can transform all external sight impressions into moral perceptions, so can one transform impressions of sound into moral perceptions. Suppose we listen to a tone and then to its octave and so attune our souls to this dual sound of a tonic note and its octave that we forget everything else, eliminate all the rest, and completely yield ourselves to these tones. It then comes about at last that instead of hearing these dual tones, our attention is directed away from them, and we no longer hear them. We find once again that in our souls a moral feeling is set free. We begin to have a spiritual understanding of what we experience when a wish lives within us that tries to lead us to something and then our reason influences our wish. The concord of wish and reason, of thought and desire, as they live in the human soul is perceived in the tone and its octave.
 In like manner we might let the most varied sense perceptions work upon us; we could in this way permit all that we perceive in nature through our senses to disappear, so that this sense veil is removed; then moral perceptions of sympathy and antipathy would arise everywhere. If we accustom ourselves in this way to eliminate all that we see with our eyes or hear with our ears, that our hands grasp, or that our understanding (which is connected with the brain) comprehends—if we eliminate all that and accustom ourselves nevertheless to stand before the world—then there works within us something deeper than the power of vision of our eyes or the power of hearing of our ears or the intellectual power of our brain thinking. We confront a deeper being of the external world. The immensity of infinity so works upon us that we become imbued with a religious mood. The green mantle of plants works upon us such that we feel and perceive in our inner being something spiritually bursting forth into bloom. The white robe of snow works upon us such that we gain an understanding of the nature of matter, of substance, in the world; we grasp the world through something deeper within us than we had hitherto brought into play. In this way we come into contact with a deeper aspect of the world itself. The external veil of nature is drawn aside, as it were, and we enter a world that lies behind this external veil. Just as when we look behind the human physical body we come to the etheric body, or life body, so in this way we enter a region in which, gradually, manifold beings disclose themselves—those beings that live and work behind the mineral kingdom. The etheric world little by little appears before us, differentiated in its details…
 Rudolf Steiner, Spiritual Beings in the Heavenly Bodies and in the Kingdoms of Nature Lecture 1, Helsinki (April 3–14, 1912)