power and materials supplied by Nature, in that case, there would be no constant capital to transfer to the product. This component of the value of the product, i.e., the £410 in our example, would be eliminated, but the sum of £180, the amount of new value created, or the value produced, which contains £90 of surplus-value, would remain just as great as if c represented the highest value imaginable. We should have C = (0 + v) = v or C' the expanded capital = v + s and therefore C' — C = s as before. On the other hand, if s = 0, or in other words, if the labour-power, whose value is advanced in the form of variable capital, were to produce only its equivalent, we should have C = c + v or C' the value of the product = (c + v) + 0 or C = C'. The capital advanced would, in this case, not have expanded its value.
From what has gone before, we know that surplus-value is purely the result of a variation in the value of v, of that portion of the capital which is transformed into labour-power; consequently, v + s = v + v' or v plus an increment of v. But the fact that it is v alone that varies, and the conditions of that variation, are obscured by the circumstance that in consequence of the increase in the variable component of the capital, there is also an increase in the sum total of the advanced capital. It was originally £500 and becomes £590. Therefore in order that our investigation may lead to accurate results, we must make abstraction from that portion of the value of the product, in which constant capital alone appears, and consequently must equate the constant capital to zero or make c = 0. This is merely an application of a mathematical rule, employed whenever we operate with constant and variable magnitudes, related to each other by the symbols of addition and subtraction only.
A further difficulty is caused by the original form of the variable capital. In our example, C' = £410 const. + 90 var + £90 surpl.; but £90 is a given and therefore a constant quantity; hence it appears absurd to treat it as variable. But in fact, the term £90 var. is here merely a symbol to show that this value undergoes a process. The portion of the capital invested in the purchase of labour-power is a definite quantity of
