We can distinguish between what may be called an ideal form of unification of humanity and the potentially vastly different attempts that will be made as humanity moves from its present state to some future reality that has had to work its way through all of the conflicting forms and forces that are operative.
Sri Aurobindo starts by providing some principles for the ideal relations between peoples, nations and the collective life of all humanity: “We have ruled out of consideration as a practical impossibility in the present international conditions and the present state of international mentality and morality the idea of an immediate settlement on the basis of an association of free nationalities, although this would be obviously the ideal basis. For it would take as its founding motive power a harmony of the two great principles actually in presence, nationalism and internationalism. Its adoption would mean that the problem of human unity would be approached at once on a rational and a sound moral basis, a recognition, on one side, of the right of all large natural groupings of men to live and to be themselves and the enthronement of respect for national liberty as an established principle of human conduct, on the other, an adequate sense of the need for order, help, a mutual, a common participation, a common life and interests in the unified and associated human race. The ideal society or State is that in which respect for individual liberty and free growth of the personal being to his perfection is harmonised with respect for the needs, efficiency, solidarity, natural growth and organic perfection of the corporate being, the society or nation. In an ideal aggregate of all humanity, in the international society or State, national liberty and free national growth and self-realisation ought in the same way to be progressively harmonised with the solidarity and unified growth and perfection of the human race.”
Sri Aurobindo, The Ideal of Human Unity, Part One, Chapter 15, Some Lines of Fulfilment, pp. 125-126