a man of letters - A man of letters is someone who knows all the words but can'

A man of letters is someone who knows all the words but can't spell his own name

"He knew the meaning of every word in the dictionary. His name? Johnson.", @WordNerd

"That man can quote Shakespeare but can't find his keys. Classic.", @LitFanatic

"He writes like he's got a PhD, but his name is spelled wrong on every book.", @GrammarHater