Reposting my now very old comment https://news.ycombinator.com/item?id=10502434 :

> Herbert Stoyan's historical work on early Lisp http://www.mcjones.org/dustydecks/archives/2010/07/29/185/ https://web.archive.org/web/20050617031004/http://www8.infor... is probably worth reading if one is seriously interested. (I haven't read much of it myself yet.) McCarthy praised Stoyan's work as better than his own 1979 HOPL paper ( http://www-formal.stanford.edu/jmc/history/lisp/lisp.html ): "Stoyan's reading of the early LISP documents gives a more accurate picture than my own memories turned out to have given." http://www-formal.stanford.edu/jmc/history/

> (As a side-note, I'm pretty sure that the broken, Wayback-beating link to "Lisp references according to Miller" on McCarthy's page is to this http://www.ai.sri.com/~delacaze/alu-site/alu/table/Lisp-Hist... document by Kent Pitman and Brad Miller (see http://www.ai.sri.com/~delacaze/alu-site/alu/table/history.h... ).)

From 2015-2018, "The Mysteries of Lisp -- I: The Way to S-expression Lisp" by Hong-Yi Dai https://arxiv.org/abs/1505.07375 ( https://news.ycombinator.com/item?id=31153702 )

> Despite its old age, Lisp remains mysterious to many of its admirers. The mysteries on one hand fascinate the language, on the other hand also obscure it. Following Stoyan but paying attention to what he has neglected or omitted, in this first essay of a series intended to unravel these mysteries, we trace the development of Lisp back to its origin, revealing how the language has evolved into its nowadays look and feel. The insights thus gained will not only enhance existent understanding of the language but also inspires further improvement of it.

Besides this first report (AIM-001), some of the reports following it in the next months are at least as important, by introducing other essential features of LISP and of many later languages:

1958-10: AIM-003 (the special form "maplist", i.e. a kind of "forall" iteration)

1958-10: AIM-004 (anonymous function definitions using "lambda"; the special form "select", which already at that early date had better syntax and semantics than the "switch" or "case" statements of later languages; the special form "search")

1959-03-13: AIM-008 (the special form "quote"; the special form "label", for defining anonymous recursive functions; also the special forms "and" and "or", a.k.a. McCarthy AND and McCarthy OR, inherited by many languages, including C)