Illustrations of exchanges of stability 547 



homologous considerations in other fields of thought \ and I shall pass 

 on thence to illustrations which will teach us something of the 

 evolution of stellar systems. 



States or governments are organised schemes of action amongst 

 groups of men, and they belong to various types to which generic 

 names, such as autocracy, aristocracy or democracy, are someAvhat 

 loosely applied. A definite type of government corresponds to one of 

 our types of motion, and while retaining its type it undergoes a slow 

 change as the civilisation and character of the people change, and as 

 the relationship of the nation to other nations changes. In the 

 language used before, the government belongs to a family, and as 

 time advances we proceed through the successive members of the 

 family. A government possesses a certain degree of stability — hardly 

 measurable in numbers however — to resist disintegrating influences 

 such as may arise from wars, famines, and internal dissensions. This 

 stability gradually rises to a maximum and gradually declines. The 

 degree of stability at any epoch will depend on the fitness of some 

 leading feature of the government to suit the slowly altering circum- 

 stances, and that feature corresponds to the characteristic denoted by 

 a in the physical problem. A time at length arrives when the 

 stability vanishes, and the slightest shock will overturn the govern- 

 ment. At this stage we have reached the crisis of a point of 

 bifurcation, and there will then be some circumstance, apparently 

 quite insignificant and almost unnoticed, which is such as to prevent 

 the occurrence of anarchy. This circumstance or condition is what 

 we typified as h. Insignificant altliough it may seem, it has started 

 the government on a new career of stability by imparting to it a new 

 type. It grows in importance, the form of goverimient becomes 

 obviously diflerent, and its stability increases. Then in its turn this 

 newly acquired stability declines, and we pass on to a new crisis or 

 revolution. There is thus a series of "points of bifurcation" in 

 history at which the continuity of political history is maintained by 

 means of changes in the type of government. These ideas seem, to 

 me at least, to give a true account of the history of states, and I 

 contend that it is no mere fanciful analogy but a true homology, 

 when in both realms of thought — the physical and the political — we 

 perceive the existence of forms of bifurcation and of exchanges of 

 stability. 



^ I considered this Bubject in my Presidential address to the British Association in 

 1905, Report of the 75th Meeting of the British Assoc. {S. Africa, 1905), London, 1906, p. 3. 

 Some reviewers treated my speculations as fanciful, but as I believe that this was due 

 generally to misapprehension, and as I hold that homologous considerations as to stability 

 and instability are really applicable to evolution of all sorts, I have thought it well to 

 return to the subject in the present paper. 



35—2 



