Foundational Texts of Mormonism: Examining Major Early Sources
edited by Mark Ashurst-McGee, Robin Scott Jensen, Sharalyn D. Howcroft
He wrote letters in his own handwriting.
"
In his
earliest history, in one of the rare passages we have in his own handwriting,
Joseph Smith wrote of learning to read and write despite limited formal education: “It required the exertions of all that were able to render any assistance for the support of the Family therefore we were deprived of the bennifit of an education suffice it to say I was mearly instructid in reading writing and the ground rules of Arithmatic which const[it]uted my whole literary acquirements.”
The majority of the time, Joseph Smith relied on scribes and clerks to compose, copy, or take down his dictation of the thousands of pages attributed to him, including sacred texts, correspondence, journals, histories, administrative records, and other documents. The scarcity of surviving records he personally wrote gives added significance to their pages."
https://www.josephsmithpapers.org/site/documents-in-joseph-smiths-handwriting
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Reading in general in early 1800's