SUPPLY AND DEMAND 
83 
expenses multiplied by its output. The last 
part of this proposition must hold because the 
employer’s remuneration, apart from pay 
ment for his capital, is represented by the 
excess of his aggregate receipts over his aggre 
gate outgoings. At "a position of perfect 
equilibrium, it may be remarked incidentally, 
this difference, in the case of the marginal 
firm, must be an amount just sufficient to have 
induced the employer of marginal capacity to 
embark on production in the industry. If it 
were more, more employers would be attracted ; 
if it were less there would eventually be fewer 
employers. Super-marginal employers, owing 
to their greater ability, may be getting more 
than they would have worked for, but they 
will not produce more than they do because it 
would not pay them, whatever they are 
earning, to manufacture an extra pair of boots 
for sale at 14s. when the addition to their 
aggregate costs would exceed 14s. 
In order that no link may be missing in 
the chain of reasoning, the above exposition 
may be supplemented by a brief survey of 
the changes which occur when demand rises. 
Demand having risen, more than 14s. a pair 
would be paid for boots, were only 12,000 
pairs obtainable, and our six firms would be 
induced to extend their operations if it were