to investigate under what conditions two borders, when placed opposite
each other, provide a continuous band of colour - that is, a
colour-band where, in place of the region of uncoloured light, green
appears. This, he observed, came about if one brought one's eye, or the
screen intercepting the light, to that distance from the prism where
the steadily widening yellow-red and the blue-violet colour-cones merge
(Fig. ii).9 Obviously, this distance can be altered by altering the
distance between the two borders. In the case of an extremely narrow
light-space, the blue and yellow edges will immediately overlap. Yet
the emergence of the green colour will always be due to a union of the
blue and yellow colours which spread from the two edges. This convinced
Goethe that it is inadmissible to place the green in the spectrum in
line with the other colours, as is customary in the explanation of the
spectrum since Newton's time.

This insight into the relation of the central colour of the continuous
spectrum to its other colours still further strengthened Goethe's
conviction that in the way man experiences nature in his soul,
objective laws of nature come to expression. For just as we experience
the colours on the blue side of the spectrum as cold colours, and those
on the yellow side as warm colours, so does green give man the
impression of a neutral colour, influencing us in neither direction.
And just as the experience of the two polar colour-ranges is an
expression of the objective natural law behind them, so too is the
experience of green, the objective conditions of whose origin give it a
neutral position between the two. With this it also became clear why
the vegetative part of the plant organism, the region of leaf and stem
formation, where the light of the sun enters into a living union with
the density of earthly substance, must appear in a garment of green.