would, if there were absolute equality of competition and absolute fluidity of labour, be measured at say 3s. It is true that no such measurement is open to us, and all such estimates are guesswork. But the idea which underlies the sentiment against "sweating" is a true one, although it has no exact practical embodiment so long as our only meaning of "value" is value in exchange at present competitive rates. It is therefore not inaccurate to represent productivity as forming the maximum wage, though we may have no exact measure of productivity at hand. The fact that any increase in productivity of labour is liable under certain circumstances of competition to pass away entirely to the consumer, is no reason for denying that an increase of productivity has taken place which might under other circumstances of competition have gone to the producer as higher wages. Though productivity as a measure of maximum wages is more or less of an unknown quantity, it is none the less true that as this "unknown" fluctuates so the possibility of high wages fluctuates. § 14. If the above analysis is correct it is not difference of sex which is the chief factor in determining the industrial position of woman. Machinery knows neither sex nor age, but chooses the labour embodied in man, woman, or child, which is cheapest in relation to the degree of its efficiency. Thus the causes which depress woman's industry are chiefly the same which depress the industry of low-skilled men and children. In each case the limits of productivity and "wants" are lower than for skilled men workers, while the terms of their competition keep their wages to the lower level and check the full incentive to efficiency. Setting aside the case of children, who are protected in some degree from the full effects of competition upon the conditions of their employment, the industrial case of women is closely analogous to that of low-skilled men. The physical weakness of the one corresponds with the technical weakness of the other so far as efficiency is concerned; in both cases the low standard of wants gives a low minimum wage, while the excessive supply of labour, rendering concerted action almost impossible, keeps wages close to the minimum.