6. There is to-day a large following for the doctrine that cost and utility are joint and equal regulators of value. Professor Alfred Marshall, for instance, states that “we might as reasonably dispute whether it is the upper or the under blade of a pair of scissors that cuts a piece of paper, as whether value is governed by utility or cost of production.”[233] Historically, there have been developed by economists two distinct and apparently antagonistic theories professing to afford ultimate explanations of value; the earlier or cost and the later or utility theory. But if it can be shown that in reality cost and utility are but joint regulators of value, recent thinkers hold this equivalent to a demonstration that the two apparently hostile doctrines are after all but the two parts of a larger harmonious whole. It is, therefore, maintained by many that the two opposed schools of value merely failed to take a broad enough view of the problem. Thus we have ever before us the interesting question of the reconciliation of the cost and utility theories. If it be desired to effect a fundamental reconciliation, what appears to be the most propitious starting point is found in the theory of the “marginal or final equivalence of utility and disutility,” a doctrine which originates purely as a theory of “subjective” or esteem value in contrast with exchange value. The first writer to give this theory a definite formulation was probably Gossen, but it was J. B. Clark’s later but entirely independent statement of the same idea which was first to bring it to the notice of economists generally.[234]