But in the present stage of machine-development the economy of the shorter working day is only obtainable in a few trades and in a few countries; the general tendency is still in the direction of an extended working day.[207] The full significance of this is not confined to the fact that a larger proportion of the worker's time is consumed in the growing monotony of production. The curtailment of his time for consumption, and a consequent lessening of the subjective value of his consumables, must be set off against such increase in real wages or purchasing power as may have come to him from the increased productive power of machinery. The value of a shorter working day consists not merely in the diminution of the burden of toil it brings, but also in the fact that increased consumption time enables the workers to get a fuller use of his purchased consumables, and to enjoy various kinds of "free wealth" from which he was precluded under a longer working day.[208] So far as machinery has converted handicraftsmen into machine-tenders, it is extremely doubtful whether it has lessened the strain upon their energies, though we should hesitate to give an explicit endorsement to Mill's somewhat rhetorical verdict. "It is questionable if all the mechanical inventions yet made have lightened the day's toil of any human being." At any rate we have as yet no security that machinery, owned by individuals who do not themselves tend it, shall not be used in such a way as to increase the physical strain of those who do tend it. "There is a temptation," as Mr. Cunningham says, "to treat the machine as the main element in production, and to make it the measure of what a man ought to do, instead of regarding the man as the first consideration, and the machine as the instrument which helps him; the machine may be made the primary consideration, and the man may be treated as a mere slave who tends it."[209]