§ 4. Since every industrial act in a modern community has its monetary counterpart, and its importance is commonly estimated in terms of money, it will be evident that the growth of capitalism might be studied with great advantage in its monetary aspect. Corresponding to the changes in productive methods under mechanical machinery we should find the rapid growth of a complex monetary system reflecting in its international and national character, in its elaborate structure of credit, the leading characteristics which we find in modern productive and distributive industry. The whole industrial movement might be regarded from the financial or monetary point of view. But though such a study would be capable of throwing a flood of light upon the movements of concrete industrial factors at many points, the intellectual difficulties involved in simultaneously following the double study, in constantly passing from the more concrete to the more abstract contemplation of industrial phenomena, would tax the mental agility of students too severely, and would greatly diminish the chance of a substantially accurate understanding of either aspect of modern industry. We shall therefore in this study confine our attention to the concrete aspect of capitalism, merely indicating by passing references some of the direct effects upon industrial methods, especially in the expansion and complexity of markets, of the elaborate monetary system of modern exchange. § 5. The inherent difficulty which besets every literary presentation of the study of a living and changing organism is here present in no ordinary degree. A book of physiology is necessarily defective in that it can neither present the just simultaneity of phenomena which occur together, nor the just sequence of phenomena which are successive. Diagrams may serve effectively to set forth tolerably simple simultaneity, but a complex diagram inevitably fails of its object; for it confuses the sight of one who seeks to simultaneously grasp the whole, and thus compels a successive examination of different parts which is generally inferior to skilled narration, in that it affords no security of the fittest order of examination of the parts. For certain simple relations between the movements of a few definite objects a working model may be serviceable; but when complex changes of shape, pace, and local relations exist, when intricate interaction takes place, and when new phenomena arise affecting by their presence all former ones, little can be effected by such visual presentment. Still less can a succession of diagrams assist us to realise the continuity of the working of such shifting forces as are presented in industrial movements.