The value of hue in all illuminations on painted glass of fine periods depends primarily on the expedients used to make the colours palpitate and fluctuate; _inequality_ of brilliancy being the _condition_ of brilliancy, just as inequality of accent is the condition of power and loveliness in sound. The skill with which the thirteenth century illuminators in books, and the Indians in shawls and carpets, use the minutest atoms of colour to gradate other colours, and confuse the eye, is the first secret in their gift of splendour: associated, however, with so many other artifices which are quite instinctive and unteachable, that it is of little use to dwell upon them. Delicacy of organization in the designer given, you will soon have all, and without it, nothing. However, not to close my book with desponding words, let me set down, as many of us like such things, five Laws to which there is no exception whatever, and which, if they can enable no one to produce good colour, are at least, as far as they reach, accurately condemnatory of bad colour. 1. ALL GOOD COLOUR IS GRADATED. A blush rose (or, better still, a blush itself), is the type of rightness in arrangement of pure hue. 2. ALL HARMONIES OF COLOUR DEPEND FOR THEIR VITALITY ON THE ACTION AND HELPFUL OPERATION OF EVERY PARTICLE OF COLOUR THEY CONTAIN. 3. THE FINAL PARTICLES OF COLOUR NECESSARY TO THE COMPLETENESS OF A COLOUR HARMONY ARE ALWAYS INFINITELY SMALL; either laid by immeasurably subtle touches of the pencil, or produced by portions of the colouring substance, however distributed, which are so absolutely small as to become at the intended distance infinitely so to the eye. 4. NO COLOUR HARMONY IS OF HIGH ORDER UNLESS IT INVOLVES INDESCRIBABLE TINTS. It is the best possible sign of a colour when nobody who sees it knows what to call it, or how to give an idea of it to any one else. Even among simple hues the most valuable are those which cannot be defined; the most precious purples will look brown beside pure purple, and purple beside pure brown; and the most precious greens will be called blue if seen beside pure green, and green if seen beside pure blue. 5. THE FINER THE EYE FOR COLOUR, THE LESS IT WILL REQUIRE TO GRATIFY IT INTENSELY. But that little must be supremely good and pure, as the finest notes of a great singer, which are so near to silence. And a great colourist will make even the absence of colour lovely, as the fading of the perfect voice makes silence sacred.