10. BRYCE: ROME AND ENGLAND 337 or prejudices, and has, while rendering much of the old law inapplicable, made a great deal of-Jiew-4e^i^tation indis- peaeabie-. Now let us consider what are the forces, influences, or conditions which at all times and everywhere become the sources and determining causes of changes in laws and insti- tutions, these latter being that framework which society constructs to meet its needs, whether administrative or economic or social. Five such determining causes may be singled out as of special importance. They are these. 1. Political changes, whether they consist in a shifting of power as between the classes controlling the government of a country, or affect the structure of the governmental machin- ery itself, as for instance by the substitution of a monarch for an assembly or of an assembly for a monarch. 2. The increase of territory, whether as added to and incorporated in the pre-existing home of a nation or as con- stituting a subject dominion. 3. Changes in religion, whether they modify the working of the constitution of the country or involve the abolition of old laws and the enactment of new ones. 4. Economic changes, such as the increase of industrial production or the creation of better modes of communication, with the result of facilitating the exchange of commodities. 5. The progress of philosophic or scientific thought, whether as enouncing new principles which ultimately take shape in law, or as prompting efforts to make the law more logical, harmonious and compendious. The influence of other nations might be added, as a sixth force, but as this usually acts through speculative thought, less frequently by directly creating institutions and laws, it may be deemed a form of No. 5. The two last of these five sources of change, viz. commerce and speculative or scientific thought, are constantly, and therefore gradually at work, while the other three usually, though not invariably, operate suddenly and at definite moments. All have told powerfully both on Rome and on England. But as the relative importance of each varies from
