360. Since matter is rigidified light, even so must it be posited in reference to colour, like light. Pure light materially substantiated or posited is _White_. The untensed æther materially posited is _Black_. 361. The mediate tensions of æther, or the mixture of Light and Dark, are mean conditions of White and Black, mixtures of the two extremes or androgynisms of White and Black. If we do not call White and Black colours, colours are then partial positions of light in matter, or in the dark. 362. Colour originates only in the _confinity_ of Light and Dark, or in the limit between White and Black. They are therefore microscopic. 363. Darkness is the cause of colours. 364. There is nothing visible but colour, but the coloured matter. The Non-corporeal itself is invisible. Darkness is the cause of all visibility. Were there no darkness, there would be no world for the eye. Colours are only illuminated darkness. 365. In the limit between Light and Dark there is neither White nor Black, but their possible mediate conditions, or the proper colours, the material tensions of æther. If the shadow-line of light be viewed under a magnifying glass, colours will be seen to reside in it. They are invisible only before on account of their minuteness. The prism and the lens do nothing else than magnify the shadow-line of light. They only show the colours that already exist therein, but do not create them. 366. There is properly only _one_ colour between White and Black; it is the transmission of light into matter generally. If we look through a prism with the refracting angle presented downwards, at an horizontal fissure in the shutter of a dark chamber, the red colour is then exhibited upon the upper and lower borders of the spectrum so formed within the eye; thus, in both instances, where the Dark is above and the White beneath, as also where the latter is above and the former beneath, as on the inferior border of the opening. Upon the lower border of the upper Red, and thus in the Clare, Yellow appears, which is consequently a mixture of Red and White, as seen through the thinner part of the prism. Yellow is thus brighter Red. Upon the upper border of the lower Red, thus also in the Clare, Blue appears, which is consequently a mixture also of Red and White, but the latter seen through the thicker part of the prism. Blue is thus offuscated Red. If Yellow and Blue be mixed, Green then originates. There can be therefore only four colours, whereof the Red is a mixture of Black and White, Yellow of Red and White, Blue of Red and Black, Green of Blue and Yellow. The first three are simple or mixed colours, the last a compound colour or a medley. These colours are parallel to the gradations in nature, or the latter are none other than the materializations of colours or the gradations of light. All other colours must be contained in the Red; it must serve as the basis or groundwork of all; it must be the noblest, most total, fullest and purest colour.