Besides aggregation of similar units, there has frequently been co-operation between units of unlike character and origin--witness symbiosis, as in lichens; the relation between many insects and flowers; the formation of flocks consisting of two or more species, as with jackdaws and rooks, and many other cases. Competition and co-operation both occur throughout the whole of evolution: but co-operation comes to play an ever more considerable part in higher forms. In lower organisms enormous overproduction is of no great consequence; their organization is simple, and, given favourable conditions, they can turn inorganic matter into their own specific substance at a great rate. But higher forms are more complex, more delicately balanced, and longer lived. Accordingly, waste of life is of greater consequence to them, and methods by which a struggle on the grand scale can be minimized tend to be more and more adopted. We find regularly, for instance, a reduction of the number of offspring in higher groups together with greater parental care. Thus co-operation, for still fresh reasons, is biologically important for the higher groups. The problem is becoming increasingly pressing for the human race, since the time is in sight when the whole habitable area of the globe will be colonized, up to a certain level of density and efficiency, by members of the more advanced races. Biologically speaking, it is perfectly clear that some co-operative system, involving federation in one form or another, is the proper system to adopt; and that the “world-state”--not necessarily organized after the plan of our present highly specialized nationalist-industrialist states, which appear happily to represent only a temporary phase of evolution, but none the less an organic reality, a co-operative unit--that the “world-state” is not merely a figment of unpractical dreamers, but an obviously desirable aim for humanity. Kant, a century and a half ago even, had seen clearly enough that some universal society was a necessity for the unfolding of human possibility; and had gone further and pointed out that there were indications of a movement of civilization in that direction. In our time, this movement has been retarded by the extraordinary and mushroom growth of Nationalism, in which to the average man his “Country” (really _Nation_) has become his most real God. In the last hundred years, Nationalism has usurped the place of Religion as the most important super-individual interest of individuals--has indeed in some sense become a religion. It is leading the world into an impasse, as do all incomplete and partial conceptions; but, in the Hague Court and the League of Nations, has already generated the seeds of what will in time devour it.[23]