It is still more important to observe that what is true of the arts is also true of the crafts, or, in other words, those kinds of manual work whose special characteristic is rare personal skill. Manual skill, though essential to material progress no less than unskilled labour is, does not, except during the earlier stages of civilisation, itself constitute an actively progressive principle. That is to say, at a very early stage in the development of productive industry manual skill reaches its utmost limits, and thenceforward remains stationary, whilst industry continues to progress. Thus the skill which is evidenced by the {254} gem-engraving of the Greeks and Romans has rarely been equalled since, and has certainly never been surpassed. But we need not stop short at the antiquity of the Greeks and Romans. Many of the implements made by the prehistoric lake-dwellers could not, so far as mere manual workmanship is concerned, be better made by any workman or mechanic of to-day. Indeed, so far is the progress of material civilisation from depending on or coinciding with any progress in manual skill, that it actually depends on a getting rid of the necessity, not certainly of all skill, but of skill of the rarer kinds. If any machine, for example, depended for its successful operation on an accurate finish in certain essential parts which only one workman in half a million could give, such a machine would be practically almost worthless. A productive machine is of use in the service of society generally in proportion as the machines or processes by which it is itself manufactured obviate the necessity for any skill in manufacturing it beyond such as can be obtained with considerable ease and constancy.