One thing we do know about ancient times is that if you were able to read and write to be able to record your thoughts in the first place, you were probably very educated and therefore had the income to be able to learn to do so. We face an incredible bias when studying the lives of ancient romans for example as the surviving documents we have from them are from the wealthy few who knew how to write, or were able to inscribe their feelings on stone. Therefore many surviving ancient documents we have are from people who were wealthy enough to have had a private education whereby language was taught to them.