Institutio Oratoria
Quintilian
Quintilian. Institutio Oratoria, Volume 1-4. Butler, Harold Edgeworth, translator. Cambridge, Mass; London: Harvard University Press, William Heinemann Ltd., 1920-1922.
He will also see that final syllables are not clipped, that the quality of speech is continuously maintained, that when the voice is raised, the strain falls upon the lungs and not the mouth, and that gesture and voice are mutually appropriate.