So without undue exaggeration we may fairly claim for the craft of the armourer a foremost place as one of the chief influences in the evolution of modern art and, as such, an important factor in the development of all the arts which follow in the train of conquest. There are certain essential rules which must be observed in the practice of every craft; but in most cases only one or two are necessary for the production of good work, because of the limitations either of the craft or of the needs of those for whom it is practised. It would be out of place to go through the various applied arts and to consider the rules which guide them; but, on examination of these rules as they apply to the craft of the armourer, it will be seen how each and all are essential for the production of satisfactory work. The rules are these:-- 1. Suitability for purpose. 2. Convenience in use. 3. Recognition of material. 4. Soundness of constructional methods. 5. Subservience of decoration to the preceding rules. It may be advantageous to examine these rules one by one and see how they are observed to the full in the best specimens of armour and how their neglect produced inferior work. 1. =Suitability for purpose.=--The object of defensive armour was to protect the wearer from attack of the most powerful weapon in use at the period when it was made. This was obtained not only by thickness of metal, but also by so fashioning the planes of the metal that they presented a “glancing surface” to the blow. An early example of this consideration of the needs of the wearer is to be found in the first additions of plate to the suit of mail which were made in the leg armour of the thirteenth century (Fig. 38). The reason for this was the increased efficacy of the weapons of the foot-soldier, who naturally attacked the legs of the mounted man. The use of mail was far from practical, except in the form of gussets or capes, which could not be made so conveniently in plate. The mail armour of the thirteenth century was only a partial protection, for although it defended the wearer from arrows and from sword-cut or lance-thrust, it was but little protection against the bruise of the blow, even when, as was always the case, a padded garment was worn underneath. Up to the sixteenth century the shield was used for this reason and provided a smooth movable surface which the knight could oppose to the weapon and thus present a glancing surface to the blow.