In every one of these modes, be it observed, the instinct of repulsion correlates with the instinct of attraction. The strifes are the strifes of combinations, of groups or masses united in themselves by sympathy, in antipathy to other groups or masses. The _esprit de corps_ arises alike in the species, the horde, the tribe, the community, the class, the faction, the nation, the trade or profession, the Church, the sect, the party. Always men unite to oppose; always they must love to hate, fraternise to struggle. The analogies in physics are obvious, but need not here be dwelt upon. There is a risk of losing concrete impressions, which are here in view, in a highly generalised statement of cosmic analogies. But it may be well to point out that a general view will perfectly reconcile the superficially conflicting doctrines of recent biologists, as to "progress by struggle" and "progress by co-operation." Both statements hold good, the two phases being correlatives. I have said that it is extremely difficult to imagine a state of society in which there shall be no public operation of any one of these forces. I am disposed to say it is impossible, but for scientific purposes prefer to put simply the difficulties of the conception. A cessation of war is not only easily conceivable, but likely; but a cessation of strife of aspiration would mean a state of biological equilibrium throughout the civilised world. Now, pure equilibrium is by general consent a state only momentarily possible; and the state of dissolution of unions, were that to follow, would involve strife of opinion at least up to a certain point. But just as evolution is now visibly towards an abandonment of brute strife among societies, so may it be reasonably expected that the strife of ideals and doctrines within societies, though now perhaps emotionally intense in proportion to the limitation of brute warfare, will gradually be freed of malevolent passion as organisms refine further. Passion, in any case, has hitherto been at once motive-power and hindrance--the omnipresent force, since all ideas have their correlative emotion. A perception of this has led to some needless dispute over what is called the "economic theory" of history; critics insisting that men are ruled by non-economic as well as economic motives.[155] The solution is perfectly simple. Men are proximately ruled by their passions or emotions; and the supremacy of the economic factor consists in its being, for the majority, the most permanent director or stimulant of feeling. Therefore, the great social rectification, if it ever come, must needs be economic.