The functions of a distant base concern more nearly the operations of a prolonged campaign. A distant base is more difficult to construct as a rule; largely because the fact of its distance renders engineering operations difficult and because the very excellence of its position as an outpost makes it vulnerable to direct attack and often to a concentration of attacks coming from different directions. If naval operations are to be conducted at considerable distance from home, say in the Caribbean Sea, distant bases are necessary, since without them, the fleet will operate under a serious handicap. Under some conditions, a fleet operating in the Caribbean without a base there, against an enemy that had established a satisfactory base, might have its normal fighting efficiency reduced 50 per cent, or even more. A fleet is not a motionless fort, whose strength lies only in its ability to fire guns and withstand punishment; a fleet is a very live personality, whose ability to fight well--like a pugilist's--depends largely on its ability to move quickly and accurately, and to think quickly and accurately. The best pugilists are not usually the strongest men, though physical strength is an important factor; the best pugilists are men who are quick as well as strong, who see an advantage or a danger quickly, and whose eyes, nerves, and muscles act together swiftly and harmoniously. A modern fleet, filled with high-grade machinery of all kinds, manned by highly trained men to operate it, and commanded by officers fit to be intrusted with such responsibilities, is a highly developed and sensitive organism--and, like all highly developed and sensitive organisms, exists in a state of what may be called "unstable equilibrium." As pointed out in previous pages, the high skill needed to perform well any very difficult task can be gained only by great practice in overcoming difficulties and eliminating errors of many kinds; and when the difficulties are manifold and great, a comparatively small increase or decrease in the overcoming of them makes a great difference in the results attained. An interesting though possibly not very correct analogy is to be seen in the case of a polished surface; for we readily note that the more highly polished the surface is, the more easily it is sullied. Another analogy may be found in the performance of a great pianist or violinist; for a very small failure in his skill for even an instant will produce a painful feeling that could not be produced by a much greater failure in an ordinary performer. Another analogy is to be found in the case of a ship that is going at the upper limit of her speed; for a very minor failure of any part of her machinery will produce a much greater slowing than it would if her speed were slower.