It is a reasonable assumption that the training of the student should result in greater discrimination, and when the exercise consists of representing, it is a matter of careful approximation of colours and values. In original design the harmonious effect depends on the individual, who, in early attempts in colour, jumps at it, being unconscious of any guiding principle. _Natural Suggestion_ It would seem that the wealth of colour combination in the various natural aspects apparent to all, would surely influence selection; that it generally fails to do so is testimony to lack of observation. Nature left alone never makes mistakes, and the colouring in flowers, land, sky, and water, the plumage of birds and other natural phenomena, is always harmonious if seen in original environment. When the balance and correct association is disturbed it is due to human interference, as is evident too often in the work of the landscape gardener and horticulturist. _Colour Scheme_ In decoration the scheme may consist of tints or tones of any one colour, and the contrast is merely that of tone; in other words, of lighter and darker phases. This method of colouring, which is quite suitable in some instances, is fairly safe, as the latitude for error is greatly reduced, but certainly is not courageous. The problem arises, when the scheme involves the use of more than one colour, and the successful effect depends on judicious association and balance. The simple rule is never to display two only of the primary colours in juxtaposition, the presence of the third being essential to harmonious and satisfactory effect. This, as a principle, forms the basis of much of the Moresque decoration, in which the details were picked out in blue and red of positive hues, and separated or outlined with gold. More consideration is required when positive or pure colour is not in request, and the proportions of juxtaposed tints have to be relative. As any tint departs from the full strength of its particular category, so those associated should be proportionately remote. Respective quantities may vary and one colour occupy relatively a small part of the surface, when to preserve the balance it may be stronger in hue than others occupying adjacent and larger areas. For such contingencies it is impossible to give exact formulæ, as the pigments employed are not always constant. In the case of manufacturers of mixed paints, it is customary to issue samples of colours for the year or season, and they cannot guarantee repeating exactly any colour or tint in subsequent mixing. The same applies where coloured papers and textiles are concerned; therefore judgment based on principle and experience can be the only guide.