The phenomenon caused much comment. James Boswell recalls conversations with Samuel Johnson in which he joked about the pig's scholarship. Johnson never saw the pig. He died just before it came to London, but he commented on a report of its show in Nottingham. He suggested that "the pigs are a race unjustly calumniated. "Pig" has, it seems, not been wanting to "man", but "man" to "pig". We do not allow "time" for his education, we kill him at a year old." Another man present joked that Alexander Pope would not have used the pig as a symbol of "the lowest degree of grovelling instinct" in his works if this creature had been known to him, but added that the pig had probably been subject to some form of torture to force it to respond to commands. Johnson replied that at least it had escaped slaughter: "the pig has no cause to complain; he would have been killed the first year if he had not been "educated", and protracted existence is a good recompence for very considerable degrees of torture." The discussion about how the pig had been trained also led to disputes about the cognitive abilities of pigs; whether the animal actually recognised letters or even words, or whether it was simply responding to direct prompting. The phenomenon was also discussed in instructional literature aimed at children, to describe the essential difference between human and animal capacities and to warn against cruelty to animals, on the assumption that the pigs were badly beaten by their trainers to force them to behave. Mrs Trimmer in her children's book "The Robin Redbreasts" (1788), "designed to teach children the proper treatment of animals", mentions the pig in chapter entitled "The Cruel Boy": aiming to teach that animals are not "mere machines, actuated by the unerring hand of Providence", it says that the sight of the Learned Pig, "which has lately been shown in London, has deranged these ideas, and I know not what think". In 1798 a learned pig appeared in the United States. William Frederick Pinchbeck displayed a "Pig of Knowledge" in New England. He claimed to have toured all the major towns of the Union and introduced the pig to President John Adams, to "universal applause". Pinchbeck later explained his methods of training the pig in a pamphlet. He denied that any form of torture was involved, insisting that it was better to "coax" the pig to follow instructions. The animal would soon learn to respond to the slightest hints of movement from the trainer.