Institutio Oratoria
Quintilian
Quintilian. Institutio Oratoria, Volume 1-4. Butler, Harold Edgeworth, translator. Cambridge, Mass; London: Harvard University Press, William Heinemann Ltd., 1920-1922.
For instance, lambda is substituted for rho, a letter which was always a stumbling-block to Demosthenes; our l and r have of course the same value. [*]( The mis-spelling of flagro as fraglo exemplifies the confusion to which Quintilian refers. A similar, though correct, substitution is found in lavacrum for lavaclum, etc. See Lindsay, Lat. Langu., pp. 92 ff. ) Similarly when c and g are not given their full value, they are softened into t and d.
Again our teacher must not tolerate the affected pronunciation of s [*]( Quintilian perhaps alludes to the habit of prefixing i to initial st, sp, sc found in inscriptions of the later Empire. See Lindsay, op. cit. p. 102. ) with which we are painfully familiar, nor suffer words to be uttered from the depths of the throat or