There are two different ways of conceiving the history of a doctrine. The historian may place himself exactly in the mental attitude of the philosopher whom he studies, and think again after him his leading ideas, as indeed he should do; but further, he can judge, just as the philosopher himself does, of the respective importance of problems, without allowing himself to distinguish what is secondary from what is essential. The historical work then assumes the shape of a “monography,” or of an “intellectual biography;” or else, while endeavouring to penetrate to the heart of the system, in order to grasp it in its principles, the historian may nevertheless place himself outside it and above it, and try to “situate” it in the general evolution of philosophy. Then the system is better understood in its entirety, since we can see its relations with the preceding, contemporary and following doctrines. At the same time it becomes possible to separate what is of enduring philosophical interest, from what was merely of secondary or momentary importance, although the author may have judged otherwise. To borrow from Comte a distinction which he often uses, the former of these methods is better suited to erudition, the latter to history. Applied to the study of his doctrine, the first method would have us to consider positive philosophy with him as simply preparatory to the Religion of Humanity, which was the first and the last goal of his efforts. The writer should undoubtedly give a large place to this “préambule indispensable,” to this great fundamental work, in which Comte lays down the intellectual bases of his political and religious system. But he ought nevertheless to subordinate it to this system and place in the front rank the “social reorganisation,” the dogma, the worship and the _régime_ of the Religion of Humanity, the institution of a spiritual power, in fact the whole of that portion of Comte’s work in which he takes up again “the Catholic programme of the Middle Ages,” confident of fulfilling it better than Catholicism itself ever did.