Institutio Oratoria

To say nothing of the language of the uneducated, we are all of us well aware that whole theatres and the entire crowd of spectators will often commit barbarisms in the cries which they utter as one man. I will therefore define usage in speech as the agreed practice of educated men, just as where our way of life is concerned I should define it as the agreed practice of all good men.

Having stated the rules which we must follow in speaking, I will now proceed to lay down the rules which must be observed when we write. Such rules are called orthography by the Greeks; let us style it the science of writing correctly. This science does not consist merely in the knowledge of the letters composing each syllable (such a study is beneath the dignity of a teacher of grammar), but, in my opinion, develops all its subtlety in connexion with doubtful points.