Religion and Science are but two parts of a correlated whole, and nothing more unfortunate in the history of civilization can be imagined than the attitude assumed by either at the present day. Having found that the Advaita was a philosophy reconciling the two, I tried to work up the idea, and placed it before the public, in a crude form, in my Raja-Yoga published in 1885. The public having taken kindly to the scheme outlined in that pamphlet; a second edition was rendered necessary. It has, however, been thought proper to replace that book by this, to explain, though neither quite definitely nor completely, yet more clearly, the method of analyzing this religion scientific philosophy. If I have laid the Advaita by the side of European Monism, it is not with any intention to criticize the latter, but only with a view to find the most convenient way of expressing the principles of the former. As in mathematics so in philosophy, it is always very convenient to express the unknown in terms of the comparatively known; without, at the same time, necessarily implying that the one is exactly equal to the other. I am aware of the danger of comparisons, and especially in a subject where even the very phraseology presents insuperable difficulties on either side; but with the explanation just given, I trust the reader will take the comparison for what it is worth, going with me, carefully, in my enunciation of the elements of Advaita philosophy.