Ep. LIV.
On Laconicism. To be laconic is not merely, as you suppose, to write few words, but to say a great deal in few words. Thus I call Homer very brief and Antimachus lengthy. Why? Because I measure the length by the matter and not by the letters.
Reproduced in full. Translation: Nicene and Post-Nicene Fathers, series 2, vol. 7 (Schaff and Wace, 1894), public domain (Public domain).