The subject of the following treatise is a new theory of colour that at its point of departure is completely different from all previous theories. It is written primarily for those who are acquainted and conversant with Goethe's colour theory. However, in addition, it will also be generally comprehensible in essentials, but all the more when one brings to it some knowledge of colour phenomena, particularly of the physiological, i.e., the appearances of colour that pertain only to the eye, of which, indeed, the most complete presentation is found in Goethe's colour theory, but which has been more or less correctly described by Buffon, Waring Darwin, and Himly.

Buffon has the honour of being the discoverer of this noteworthy fact, which is important, indeed, indispensable for a true understanding of the essence of colour illuminated bymy theory. Goethe, however, has opened the way for a discovery of this fact through a two-fold service. First, he broke the old spell of Newton's incorrect theory and thereby reasserted freedom of thought about this subject, for, as Jean-Paul correctly observed ‘every revolution expresses itself sooner, more readily, more intensely, as polemic than as thetic’ (Aesthetics, Vol. 3, p. 861). But this service will gain recognition when the lecterns and writing desks are occupied by a completely new generation, which – had it only been so with their elders – does not have to jeopardize its own honour in overturning a theory on which they had lectured throughout their lives not as a matter of faith, but as a matter of conviction. – Goethe's second service is that in his excellent work he delivered in full measure what the title promised: data for a theory of colour. There are important, complete, significant data, rich material for a future theory of colour. However, he did not undertake to provide this theory itself; for this reason (as on p. xxxix of his Introduction), he even notes and admits that he presented no actual explanation of the essence of colour, but actually postulated it as a phenomenon and only shows how it comes about, not what it is. Physiological colours, which are my point of departure, he lays down as a complete phenomenon, existing independently, without even attempting to bring them into connection with the physical colours, which are his principal theme.