Institutio Oratoria
Quintilian
Quintilian. Institutio Oratoria, Volume 1-4. Butler, Harold Edgeworth, translator. Cambridge, Mass; London: Harvard University Press, William Heinemann Ltd., 1920-1922.
The practice of joining e and i as in the Greek diphthong ει lasted longer: it served to distinguish cases and numbers, for which we may compare the instructions of Lucilius:
- The boys are come: why then, their names must end
- With e and i to make them more than one; and later—
But this addition of e is quite superfluous, since t can be long no less than short:
- If to a thief and liar ( mendaci furique ) you would give,
- In e and i your thief must terminate.
it is also at times inconvenient. For in those words which end in i and have e as their last letter but one, we shall on this principle have to write e twice: I refer to words such as aurei or argentei and the like.
Now such a practice will be an actual hindrance to those who are learning to read. This difficulty occurs in Greek as
some wrote ai in all cases, as in Greek, others confined its use to the dative and genitive singular; whence it comes that Vergil, [*](Aen. ix. 26 and vii. 464. ) always a passionate lover of antiquity, inserted pictai uestis and aquai in his poems.
But in the plural they used e and wrote Syllae, Galbae. Lucilius has given instructions on this point also; his instructions occupy quite a number of verses, for which the incredulous may consult his ninth book.
Again in Cicero's days and a little later, it was the almost universal practice to write a double s , whenever that letter occurred between two long vowels or after a long vowel, as for example in caussae, cassus, diuissiones. That he and Vergil both used this spelling is shown by their own autograph manuscripts.