The transparency of plant colours makes it possible to intensify the colour by layering - so shifting bright yellow, for instance, towards orange. In view of the fact that the colours contain their complementary colours, the plant colour circle resembles the colour circle of Goethe. In his contemplation of colour as a natural phenomenon, Goethe observed that the relation between light, dark and turbidity evokes certain colour shifts. This gives rise to the blue of the sky, for instance, in that light shines through the atmosphere that has been illuminated by the sun (a turbid medium) against the dark backdrop of the cosmos. The yellow to purple colours of sunrise and sunset come about when white sunlight shines through the darker atmosphere (a concentrated turbid medium).

Similar results are observed in the layering of plant colours, when for example we find a trace of violet in the brighter colour layers of the orange derived from yellow camomile, whereas orange predominates in the middle colour layers; and when the colour is heavily applied, what we get is a gleaming red. The colour crystal and the white paper that shines through are analogous here to the source of light; the application of the colour represents the more or less concentrated turbidity.