Institutio Oratoria

Nor yet again must we adopt all the gestures and movements of the actor. Within certain limits the orator must be a master of both, but he must rigorously avoid staginess and all extravagance of facial expression, gesture and gait. For if an orator does command a certain art in such matters, its highest expression will be in the concealment of its existence. What then is the duty of the teacher whom we have borrowed from the stage?

In the first place he must correct all faults of pronunciation, and see that the utterance is distinct, and that each letter has its proper sound. There is an unfortunate tendency in the case of some letters to pronounce them either too thinly or too fully, while some we find too harsh and fail to pronounce sufficiently, substituting others whose sound is similar but somewhat duller.