Upon exactly parallel lines lie the references to causality in the controversy. In the physical realm events may recur, but in the mental realm the same thing can never happen again because we are living in real, flowing time, or la duree, and our conscious states are changing. Admitting that there is that in experience which warrants the application of the principle of causality, taking that principle as the statement that physical phenomena once perceived can recur, and that a given phenomenon, happening only after certain conditions, will recur when those precise conditions are repeated, [Footnote: See the brief paper Notre croyance a la loi de causalite, Revue de metaphysique et de morale, 1900.] still it remains open whether such a regularity of succession is ever possible in the human consciousness, and so the assertion of the principle of causality proves nothing against Freedom. We may admit that the principle is based on experience--but what kind of experience? Consideration of this question leads us to assert that the principle of causality only tends to accentuate the difference between objects in a realm wherein regular succession may be observed and predicted and a realm where it may not be observed or predicted, the realm of the self. Just because I endure and change I do not necessarily act to-day as I acted yesterday, when under like conditions. We do expect, however, that this will not be the case in the physical realm; for example, we expect that a flame applied to dry paper will always set it alight. Indeed, the more we realize the causal relation as one of necessary determination, we come to see that things do not exist as we do ourselves, and distinction between physical and psychical events becomes clear. We perceive that we, in ourselves, are centres of indetermination enjoying Freedom, and capable of creative activity.