I have always said⁠—and have proved by experiment⁠—that the most powerful soporific is sleep itself. After having slept profoundly for two hours, having fought against so many giants, and formed so many lifelong friendships, it is far more difficult to awake than after taking several grams of veronal. And so, reasoning from one thing to the other, I was surprised to hear from the Norwegian philosopher, who had it from M. Boutroux, “my eminent colleague⁠—pardon me, my brother,” what M. Bergson thought of the peculiar effects upon the memory of soporific drugs. “Naturally,” M. Bergson had said to M.