Pictorially _rhythm_ is best gauged by certain tapestries based on the flower backgrounds of Fergusson and Anne Estelle Rice. Assume a black square of cloth; if the flowers are grouped thus from left to right: dark red, pink, white, there is no rhythm, for the mental line is a mere downgrade; if they are grouped: dark red, light blue, dark green, there is no rhythm, for the mental line is a mere curve, a circular or perhaps parabolic basin; but if the grouping amounts to: dark red, pink, light blue, black, light green, cream, dark brown, there is a succession of ebb and flow, rise and fall, _rhythm_. And this applies to drawing also, if we accept that colour is indicated by line, that lines are colours and that colours are tenses. That line can indicate colour is beyond denial, for we accept that colour is not material while tone is material. Colour being the _relation_ between an impression and the impression of colourlessness, and tone being the resultant translation of the intensity of the colour, then it is feasible to reproduce a red and blue combination by a green and yellow combination of equal contrast.[9] Therefore a combination of blacks may be made to balance a combination of even seven colours, provided the relative intensity (amount) of the blacks is in a true relation, in tone, with the relative intensity of the colours. C. R. W. Nevinson achieves this with grays and blacks, while Wyndham Lewis forgoes it. [Footnote 9: Hence, _if the colour relations are maintained_, it is correct to represent a blue-eyed rubicund man by red eyes and a violet face.] The quality of _rhythm_ being obvious in music needs no discussion; it is the only form of rhythm the popular can recognise, but if we accept the principles of grouping in phrase and colour, no musician will fail to recognise a sarabande in a dance of Matisse or in the posturings of Kellermann's clown. As for _intensity_, with which goes _reaction_, for the first cannot exist without the second, it is naturally brought about by the rhythmic focusing of the subject's attention upon words, colours or notes. Intensity is marked, for instance, by the triplets of the Venusberg music, their continual slow billowing; it can be found, less easily, in phrases and colours, but it must exist if the work is art. In prose it is marked by a general nervousness of form and word:-- 'Upon the crag the tower pointed to the sky like a finger of stone, and about its base were thick bushes, which had burst forth into flower patches of purple and scarlet. The air was heavy with their scent.'