The exact proportion which charges should bear to the field cannot, of course, be stated with accuracy, there being no ready means of measurement, even if such were desirable, and it must necessarily remain a matter for artistic perception to find the just mean between crowding a space and failing to fill it. It is evident also that the proportion would be modified by circumstances, such as the character of the charge (whether condensed or dispersed), and also to some extent by colour, with regard to the respective effects of light on dark or dark on light as affecting apparent size. It may, however, be suggested that the charges should be insisted upon to the fullest extent that is compatible with the general style of the design, the field remaining of such weight that the Scottish quarter of the Royal Banner, for example, if seen as a mass at a distance, will tell as gold rather than red. And after all is said, the actual balance must be left to the decision of the trained eye. When strong outline filled in with colour is the method of working, due allowance must be made for the tendency of the line to become merged in the darker of the two tinctures; and the object will therefore need to be drawn slightly larger or smaller accordingly. There are also illusions of an optical nature that are produced by certain combinations of lines. If, for instance, three pallets are charged upon a chevron, it will be found that the middle one must be appreciably wider than those beside it if the three are to appear equal. Fig. 88 shows this, though the fact is more clearly appreciable in a drawing on a larger scale. [Illustration: FIG. 88.] The Pose of the Animals must be carefully observed as being of the utmost heraldic importance, and must in the main be adhered to with complete fidelity. To neglect in this respect is due much of the bad heraldry which too often vitiates otherwise good work. In the early days of the science, when the bearings were few, the nature of the creature was, no doubt, sufficient for the intended purpose, for there would be no other near with which to confuse it, and the pose was probably dictated by the form of the space that the animal was required to fill, but when it became necessary to distinguish between different bearers of the same animal, pose assumed a special significance and therefore became one of the principal means of heraldic distinction.