Once this is practically carried out, we may expect a complete colour-circle to appear as already divined by Goethe. The full circle consists of twelve discernible colours, with the Goethean peach-blossom diametrically opposite the green. It is in this region of the peach-blossom that - again according to Rudolf Steiner - we shall find a source of actively working life-forces, springing from the fourth metamorphosis of levity. Such is the prospect for research work guided on the new lines. POSTSCRIPT The fact of our having disclosed here one of Rudolf Steiner's indications concerning as yet undetected possibilities of scientific research, makes it necessary to deal with an objection which may be raised, particularly by some readers who already know this indication through their own relation to Rudolf Steiner's work. They may object to a discussion of the subject in a publication such as this, feeling it dangerous to hand over to the world information which in the economic battles of to-day might be used in a sense contrary to the social-moral aims to which the work of Rudolf Steiner was dedicated. In reply it may be said that all we have gone through in this book has shown that concrete knowledge of the world cannot be gained without a certain ethical effort by the seeker. Therefore, anyone who receives such knowledge with a passive attitude of soul will find it meaningless, and will be quite unable to turn it to practical account. We may therefore rest assured that the solution of the problem related here, as of any other experimental task set by Rudolf Steiner, will contain in itself a guarantee that no use will be made of it detrimental to the true progress of mankind. On the other hand, the present world-situation, which to so high a degree is determined by the vast liberation of the sub-physical forces of the earth, makes one feel it is essential not to close the considerations of the fields of knowledge dealt with in these chapters, without a hint at the practical possibilities which arise from a continuation of Goethe's strivings in this field. 1 See, in Rudolf Steiner's edition of Goethe's scientific writings, his footnote to Goethe's criticism of Nuguet's theory of the spectrum in the historical part of the Farbenlehre (Vol. IV, p. 248, in Kürschner's edition). 2 It is obvious that the reader who wishes to appreciate fully the significance of the observations described in the following paragraphs, must, as in previous cases, carry out these observations himself. 3 In this and the two following diagrams the light-realm has been represented as being less wide than the space obtained by the prism. To avoid unnecessary complexity the colours which, in such a case, actually appear at the border of the light-realm where it emerges from the prism are not shown in any of the diagrams.