“On Some of the Mental Affections of Childhood and Youth: Lecture 3: Idiot Savants”, 1887 (; backlinks):
…One youth was under my care who could build exquisite model ships from drawings, and carve with a great deal of skill, who yet could not understand a sentence—who had to have it dissected for him, and who, when writing to his mother copied verbatim a letter from The Life of Captain Hedley Vicars, by Miss Marsh, although it had not the slightest appropriateness in word or sentiment.
…Extraordinary memory is often met with associated with very great defect of reasoning power. A boy came under my observation who, once having a book, could ever more remember it. He would recite all the answers in Magnall’s Questions without an error, giving in detail the numbers in the astronomical division with the greatest accuracy. I discovered, however, that it was simply a process of verbal adhesion. I once gave him Gibbon’s Rise and Fall of the Roman Empire to read. This he did, and on reading the third page skipped a line, found out his mistake and retracted his steps; ever after, when reciting from memory the stately periods of Gibbon, he would, on coming to the third page, skip the line and go back and correct the error with as much regularity as if it had been part of the regular text.
…Another boy can tell the tune, words, and number of nearly every hymn in Hymns Ancient and Modern.
[confabulation] …Improvisation is an occasional faculty. I had a boy under my care who could take up a book, pretending to read, an art he had not acquired, and improvise stories of all kinds with a great deal of skill, and in any variety, to suit the supposed tastes of his auditors. [So savants can confabulate just like an LLM; why does this come up so little? Does no one ever test them on ‘trick’ questions, because they are too focused on the positive case? Or do they refuse to cooperate if it’s outside their special areas of interest?]
…In none of the cases of “idiot savant” have I been able to trace any history of a like faculty in the parents or in the brothers and sisters…All of these cases of “idiot savants” were male; I have never met with a female.
…a boy who had a very unusual faculty, of which I have never since met another example, viz. the perfect appreciation of past or passing time. He was 17 years of age, and although not understanding, so far as I could gather, the use of a clock-face, could tell the time to a minute at any part of the day, and in any situation. I tried him on numberless occasions, and he always answered with an amount of precision truly remarkable. [2002 discuss a recent example of savant time-keeping, Ellen Boudreaux.]