In every living organism, in fact, there is a principle of stability and a principle of movement. The identity of a human being persists through all the modifications, internal and external, which he undergoes. So with the language of a people; and so with every historical religion. Its fundamental and regulative principle is the relation it establishes between the soul and God. The form or external realisation of this principle depends, no doubt, on the race, the geographical environment, the historical period. It will vary therefore with these circumstances. But the religious type or organic principle remaining the same, this religion will appear the same throughout the incessant movement of its dogmas, rites, and symbols. This is the very condition of its life. Forms which cannot bend, symbols whose fresh and living interpretation is exhausted, a rigid body that no longer assimilates or eliminates any external element, represent a state of sterility and death, to be followed by a speedy dissolution. Pious men are right in clinging obstinately to the stability of their principle of piety, but they ought to cling as tenaciously to the renewal of forms and ideas in their religion; for this is the only proof that their treasure has kept its value, and their religious principle its organising virtue. The life of a religion is measured by this power of adaptation and renovation. If Christianity is the universal and eternal religion, it is because its virtuality in this respect is infinite. * * * * * Before I close, let me try to prevent two misunderstandings. In saying that in dogmas we must distinguish the religious substance and the intellectual form, I do not mean that we either can or ought to isolate them from each other, or that we can ever hope to have them separately. Piety is only conscious for us and discernible by others when incarnate in its expression or intellectual image. A religion without doctrine, a piety without thought, a feeling without expression, these are things essentially contradictory. It is as vain to wish to seize pure piety, as in philosophy it is to seek to define "the thing in itself." When we speak of the inward religious fact, then, of pious experience, we do not speak of a bare experience; we speak of a psychological phenomenon, of a precise and, consequently, formulated experience. In the second place, for religious science, it is not a question of isolated experience, of the experience of a single individual. The material would be too precarious, and the field of observation too limited. The question refers to the individual life in its continuity, and to the life of the religious society considered in its historical development.