I have read portions of Yeats' "A Vision" quoted online, seeking to determine what and how Yeats learned ancient source texts.
Apparently Yeats wanted to look into cabbalistic texts
to derive his system of personality, but never actually did. Instead, it looks like Yeats stopped at the language barrier and depended on others to digest source material. Thus it seems Yeats' system is based on his understanding of his aquaintances' translations/interpretations to him.

In a similar situation, James Joyce actually learned the languages of original cabbalistic texts. Joyce's written works after his cabbala are, linguistically, remarkably different than before. At least a great change in Joyce's writing is approximately close enough to his own language study, learning to read Hebrew and Aramaic, to speculate that the material in original languages added to his reading, influenced him toward the subjective shorthand he adopted in his writing style. Joyce became the adopted "bohemian" or son-in-law mentioned in my comments and reveiews of Sir Walter Scott and Robert Louis Stevenson/