Nevertheless, the compensation of a decrease in the number of
 labourers employed, or of the amount of variable capital advanced by a
 rise in the rate of surplus-value, or by the lengthening of the working-day,
 has impassable limits. Whatever the value of labour-power may be, whether
 the workingtime necessary for the maintenance of the labourer is 2 or 10
 hours, the total value that a labourer can produce, day in, day out, is
 always less than the value in which 24 hours of labour are embodied, less
 than 12s., if 12s. is the money expression for 24 hours of realised labour.
 In our former assumption, according to which 6 workinghours are daily necessary
 in order to reproduce the labour-power itself or to replace the value of
 the capital advanced in its purchase, a variable capital of 1,500s., that
 employs 500 labourers at a rate of surplus-value of 100% with a 12 hours’
 working day, produces daily a surplus-value of 1,500s. or of 6 × 500 workinghours.
 A capital of 300s. that employs 100 labourers a day with a rate of surplus-value
 of 200% or with a working day of 18 hours, produces only a mass of surplus-value
 of 600s. or 12 × 100 workinghours; and its total value-product, the equivalent
 of the variable capital advanced plus the surplus-value, can, day in, day
 out, never reach the sum of 1,200s. or 24 × 100 workinghours. The absolute
 limit of the average working day — this being by nature always less than
 24 hours — sets an absolute limit to the compensation of a reduction of
 variable capital by a higher rate of surplus-value, or of the decrease of
 the number of labourers exploited by a higher degree of exploitation of
 labour-power. This palpable law is of importance for the clearing up of
 many phenomena, arising from a tendency (to be worked out later on) of
 capital to reduce as much as possible the number of labourers employed
 by it, or its variable constituent transformed into labour-power, in contradiction
 to its other tendency to produce the greatest possible mass of surplus-value.
 On the other hand, if the mass of labour-power employed, or the amount
 of variable capital, increases, but not in proportion to the fall in the
 rate of surplus-value, the mass of the surplus-value produced, falls.