In his correspondence with Stuart Mill which takes place between 1841 and 1846, that is to say which embraces the end of his first career and the beginning of the second, Comte has repeatedly explained how the two successive portions of his work are connected together, and in what they are distinct. It may not be useless to quote his own words. “The second half of my philosophical life,” he says, “must differ notably from the first, especially in that feeling must take, if not an obvious, at least a real part in it, one as great as that of the intellect. The great work of systematization which has been reserved for our century, must indeed embrace equally, both feelings and ideas as a whole. Truly it was the ideas which had first to be systematized, under pain of failing to bring about a complete regeneration by falling into a more or less vague mysticism. That is why my fundamental work had to appeal almost exclusively to the intellect. It was to be a work of research, and accessorily of discussion, destined to discover and to constitute the true universal principles, in rising by hierarchical degrees from the simplest scientific questions to the highest social speculations.”8 But this being done, Comte passed to the systematisation of the feelings, “a14 necessary sequel to that of the ideas, and an indispensable basis for that of the institutions.”