Achilles was the son of a goddess and of a mortal; in that, he is the image of the genius of war. The divine part is all that that is derived from moral considerations of character, talent, the interest of your adversary, of opinion, of the temper of the soldier, which is strong and victorious, or feeble and beaten, according as he believes this divine part to be. The mortal part is the arms, the fortifications, the order of battle - everything which arises out of material things.