The principle of causality and the principle of the conservation of energy are m themselves scientific “shibboleths,” and neither of them, asserts Boutroux, can be worked out so absolutely as to justify themselves as ultimate descriptions of the universe. They are valuable as practical maxims for the scientist, whose object is to follow the threads of action in this varied world of ours. They are incomplete, and have merely a relative value. Philosophy cannot permit their application to the totality of this living, pulsing universe. For cause, we must remember, does not in its strictly scientific meaning imply creative power. The cause of a phenomenon is itself a phenomenon. “The positive sciences in vain pretend to seize the divine essence or reason behind things.”[36] They arrive at descriptive formulæ and there they leave us. But, as Boutroux well reminds us in concluding his thesis, formulas never explain anything because they cannot even explain themselves. They are simply constructions made by observation and abstraction and which themselves require explanation. [36] _Contingence des Lois de la Nature_, p 154. The laws of nature are not restrictions which have been, as it were, imposed upon her They are themselves products of freedom; they are, in her, what habits are to the individual. Their constancy is like the stability of a river-bed which the freely running stream at some early time hollowed out. The world is an assembly of beings, and its vitality and nature cannot be expressed in a formula. It comprises a hierarchy of creatures, rising from inorganic to organic forms, from matter to spirit, and in man it displays an observing intelligence, rising above mere sensibility and expressly modifying things by free will. In this conception Boutroux follows Ravaisson, and he is also influenced by that thinker’s belief in a spiritual Power of goodness and beauty. He thus leads us to the sphere of religion and philosophy, both of which endeavour, in their own manner, to complete the inadequacy of the purely scientific standpoint. He thus stands linked up in the total development with Cournot and Renouvier, and in his own group with Lachelier, in regard to this question of the relation of philosophy and the sciences.