A volume on the relations of sense and thought, like Condillac’s, is not the place to which one naturally turns in search of information about a girl who loyally served a proscribed Prince and a forsaken Cause. Yet it is Condillac who attests for us ‘the keenness, the just balance, of Mlle. Ferrand’s intellect, and the vivacity of her imagination, qualities apparently incompatible, when carried to the pitch at which she displayed them.’ The scheme of Condillac’s psychology cannot be discussed in this place, but he says that he owed everything to Prince Charles’s friend. ‘She enlightened me as to the principles, the plan, and the most minute details, and I ought to be the more grateful, as she had no idea of instructing me, or of making a book. She did not remark that she was becoming an author, having no design beyond that of conversing with me on the topics in which I was interested.... Had she taken up the pen, this work would be a better proof of her genius. But there was in her a delicacy which forbade her even to contemplate authorship.... This treatise is, unhappily, but the result of conversations with her, and I fear that I may have sometimes failed to place her ideas in their true light.’ Had Mlle. Ferrand survived, Condillac thinks that she would not have allowed him to acknowledge her influence on his work. ‘But how can I, to-day, deny myself the pleasure of this act of justice? Nothing but this remains to me, in our loss of a wise adviser, an enlightened critic, and a true friend. You, Madame, will share the pleasure with me, you who will not cease to regret her while you live.’ The philosopher speaks of ‘the intellect, the loyalty, the courage, which formed these ladies for each other.’ Loyalty, courage, wit, these women laid them at the feet of a Prince not their own, and solely recommended to their tenderness by his misfortunes. ‘Your friend, in dying, had this one consolation, Madame, that she was not to survive you. I have seen her happy in this reflection. “Speak sometimes of me with Madame de Vassé,” she said to me, “and let it be with a kind of pleasure.”’ Such was the girl, so brilliantly endowed, so brave, so affectionate, who did Prince Charles’s marketing, bought him novels and razors, directed his choice of books, was the channel through which his secret correspondence passed, was jealously regarded by his mistress, Madame de Talmond, and died before the end of all hope had come, before the Prince was renounced even by his own. To the angry Madame de Talmond she wrote, ‘I am strongly attached to your friend [the Prince] and for him would do and suffer anything short of stooping to an act of baseness.’ There must have been something in Charles, beyond his misfortunes, to win so much devotion from a woman of the highest intellect.