The remembrance of screams, or other sounds heard in Brazil, when he was powerless to interfere with what he believed to be the torture of a slave, haunted him for years, especially at night. In smaller matters, where he could interfere, he did so vigorously. He returned one day from his walk pale and faint from having seen a horse ill-used, and from the agitation of violently remonstrating with the man. On another occasion he saw a hors-breaker teaching his son to ride, the little boy was frightened and the man was rough; my father stopped, and jumping out of the carriage reproved the man in no measured terms. One other little incident may be mentioned, showing that his humanity to animals was well-known in his own neighbourhood. A visitor, driving from Orpington to Down, told the man to go faster, "Why," said the driver, "If I had whipped the horse THIS much, driving Mr. Darwin, he would have got out of the carriage and abused me well." With respect to the special point under consideration,--the sufferings of animals subjected to experiment,--nothing could show a stronger feeling than the following extract from a letter to Professor Ray Lankester (March 22, 1871):-- "You ask about my opinion on vivisection. I quite agree that it is justifiable for real investigations on physiology; but not for mere damnable and detestable curiosity. It is a subject which makes me sick with horror, so I will not say another word about it, else I shall not sleep to-night." An extract from Sir Thomas Farrer's notes shows how strongly he expressed himself in a similar manner in conversation:-- "The last time I had any conversation with him was at my house in Bryanston Square, just before one of his last seizures. He was then deeply interested in the vivisection question; and what he said made a deep impression on me. He was a man eminently fond of animals and tender to them; he would not knowingly have inflicted pain on a living creature; but he entertained the strongest opinion that to prohibit experiments on living animals, would be to put a stop to the knowledge of and the remedies for pain and disease."