Specifically the spell-casting system was heavily inspired by the magic in Jack Vance's "Dying Earth" series of books which dates back to the 1950's.
From Wikipedia:
Quote
Magic in the Dying Earth is performed by memorizing syllables, and the human brain can only accommodate a certain number at once. When a spell is used, the syllables vanish from the caster's mind. Creatures called sandestins can be summoned and used to perform more complex actions, but are considered dangerous to rely upon. Magic has loose links to the science of old, and advanced mathematics is treated like arcane lore.

Interesting article about the influence of Vance on the creation of DND.
https://goodman-games.com/blog/2022/03/11/jack-vances-influence-on-dungeons-dragons/