Fine colour implies a unified relationship, in which each part is subordinate to the whole, and the transitions between them are felt to be as precious and beautiful as the colours themselves. In fact, the colours themselves must be continuously modified and broken as part of the transition. Ruskin said in his Elements of Drawing, 'Give me some mud off a city crossing, some ochre out of a gravel-pit, a little whitening, and some coal dust, and I will paint you a luminous picture, if you give me time to gradate my mud, and subdue my dust.' In many works by the greatest colourists - Rembrandt and Watteau are examples - there are very few identifiable colours.