We observe the systematic development of ever-larger groupings of humanity. The imperial form has been tried on multiple occasions, but it was not stable and eventually dissolved. The largest current stable grouping is the nation, and we see nations proliferating around the world. The nation-unit is stable, not just because it speaks to physical and vital needs of particular people, but because it has the power of a psychological unity among the members of that nation. Unstable nations are those that do not have this kind of psychological unity, and they have tended to break up, or reform with other nations, or carve out a new national unit in response to the centrifugal forces at work in the absence of psychological unity. The recurring attempts to develop yet larger units, along with the rise of the idea of the religion of humanity, are signs that Nature has not completed its work of unifying humanity. This process continues to evolve, developing new justifications, and confronting new concerns that can only be solved by a united effort of humanity.
Sri Aurobindo observes: “…while it is possible to construct a precarious and quite mechanical unity by political and administrative means, the unity of the human race, even if achieved, can only be secured and can only be made real if the religion of humanity, which is at present the highest active ideal of mankind, spiritualises itself and becomes the general inner law of human life.”
“The outward unity may well achieve itself, — possibly, though by no means certainly, in a measurable time, — because that is the inevitable final trend of the working of Nature in human society which makes for larger and yet larger aggregations and cannot fail to arrive at a total aggregation of mankind in a closer international system.”
Sri Aurobindo, The Ideal of Human Unity, Part Two, Chapter 35, Summary and Conclusion, pg. 301