Sri aurobindo discusses the inevitability of the unification of the human race as a result of imperative evolutionary forces,presents the principles which could be followed in the process of such unification,describes the need for fulfilling the principle of individual and group freedom within the human unity,and argues that it is the growth of thereligion of humanity which alone will ensure a world union that advances the spiritual evolution of the race. Originally written and published in monthly instalments in the journal arya between september 1915 and july 1918,the book in its current form was revised by sri aurobindo during the late 1930s,and again in 1949 when he brought it up to date mainly by the addition of a postscript chapter.