"He came upon many evenings, and sometimes worked with me till daybreak. I was disappointed on finding that his chief interest was in the lower branches of chemistry--that his ardour for great discoveries was less than my own. He took an ardent delight in the more curious kinds of drugs, whether of a curative or a poisonous nature. He was keenly interested in the secrets of Don Antonio Medici, whose skill in poisons was famous in the early part of the century; and he pored with delight over the records of execution by poison as ordered by the Council of Ten; and in the experiences of Brother John of Ragusa, who suggested to the Tribunal various admirable methods of mysteriously causing death. He had strange theories about the poisons and medicines of the ancient world and of the Middle Ages, and asked my permission to experiment with certain vegetable and mineral poisons upon stray curs and rabbits which he brought secretly to my laboratory. I think it was his callousness to the pain of these animals which first gave me a feeling of revulsion against him. "One evening, when he left me rather earlier than usual, the door of the family sitting-room was open as I conducted him down-stairs, and he was surprised at the beauty of my granddaughter's voice. She was seated at her harpsichord, singing an _Agnus Dei_, and he could see her in the lamplight as we passed the door. He pretended to be enraptured by her singing, but was discreet enough to make no remark upon her beauty, which was very striking as she sat with uplifted countenance, her face radiant in the lamplight, her soul looking out of her eyes in a religious ecstasy. "A week passed after this, in which I saw Louis only on two evenings, during both of which he occupied himself chiefly in his study of toxicology. On one occasion, when I had been particularly disgusted by the tortures he had inflicted upon a helpless cur which he had captured in his evening walk, and upon which he had been trying the effect of small doses of aconite, I taxed him with the brutality and uselessness of his experiments. "'I grant that the taste is somewhat morbid,' he said; 'but since I have been in Italy I have been studying the history of your Borgias and your Medicis, and I have a philosophical pleasure in imagining their ideas and realising their excitement in little. I can imagine now that this stray cur is a powerful enemy whose life I am slowly sapping. I can feel as your Italian Catherine, our Queen-mother, felt when her son's frail body wasted slowly under her diabolical arts, to make way for that other son whom she loved so much better.' "'Such a woman was incapable of love!' I exclaimed; 'she was made up of policy and self-interest, and if she preferred Henry to Charles it was because she thought she could more easily govern France with Henry for her mouthpiece.'