Secretary

Not everyone could write -- the secretary wrote for them, transferring their thoughts onto paper (or parchment).

Not everyone could write well -- the secretary cast their spoken words into clear language for them.

Not everyone could write legibily -- the secretary wrote (generally) in a clear hand which others could read, even where the language was different.

Not everyone knew the same language -- the secretary could use Lingua Franca to ensure that "all men" had a chance of understanding his patron's message.

Some secretaries were also companions, chroniclers, factotums and body-servants for their patrons. Some even, over time, came to serve more than one patron, as their fame grew or fell, and their patrons' wealth fluctuated.