So I was reading about Milton Erickson who is possibly one of the most important people in the history of hypnotism

And it said that he read "the dictionary" or "a dictionary" when he was young

I do not believe that it would be practical to read a modern dictionary because of so many new internet slang words, ebonics, and new words in taxpayer subsidized academic fields

But could I do something similar with dictionaries from modern English times but before there were so many words?