THE THEORY OF MODERN WELFARE 181
business enterprise habitually ran its course within commercial traffic proper, apart from the industrial process aa such, so long these recurring periods of depression and exaltation began and ended within the domain of commerce.' The greatest field for
1 This means, in concrete terms, prior to the regime ol the macbini industry. Since the coming in of the machine, modern business ei prisa ha« labeii over the maaagemetit of industry -, that U to say, industry has come to ha managed by the method of investment for a profit — by what is in aim and anitnua easenlially the commercial method. As has been reioarlted above, capital has become vendible in a dscisiTe degree. The material factors engaged in industry, particularly in the machine industry proper, are vendible In about the same (perhaps on an average in a higher) degree as tbe material items handled by commercial traffic arc vendible. This is true of raw materials, labor power, and industrial equipment, but it is peculiarly true of the industrial equipment — the mechanical factors in the strict«r sense. It is in these mechanical appliances primarily, but in the other factoia of the machine Industry in only a slightly lower degree, that the traffic of investment, and of purchase and sale connected with Investment, is particularly active. Within these wider limits a further limitation may be made. " Vendibility" of all ii«ms involved is. as a broadly general rule, carried to the highest pitch in those branches of industry that have to do with the production of •■ producer's goods." These branches are at the same time, and partly in consequence of this fact, more widely and intimately related to other branches of Industry than are any other group of industrial processes that might be named. It SMms to he this extreme prevalence of vendibility, together with this more far-reaching and more exacting articulation with the industrial process at large, that chiefly gives substantial signlQcance to a clsMiflcatioti of these lines of industry as " Produktivraittel-Industrien " by lat« German writers. There is, for