Friday is for rhetoric! Quintilian engages in the art of backpedaling in book 1 chapter 7. Are grammar and spelling descriptive or prescriptive? Yes, this is the kind of thing we talk about at the dinner table sometimes.
Quintilian, and J.S. Watson. Institutes of Oratory. Edited by Lee Honeycutt, 2010. Kindle Electronic Edition. Book I Chapter 7
After spending chapter six discussing language choice in speaking, Quintilian discusses rules for writers. He criticizes what the Greeks call orthography. Specifically he questions the need to write macrons where they are obvious or not necessary for understanding. Also spelling of compounds he questions (Quintilian I.7.6). In the instance of the letter K, borrowed from Greek, he confirms a dislike of usage. “But orthography submits to custom and has therefore frequently been altered” (Ibid., I.7.11). He observes a number of instances of spelling change over the centuries of Latin literature and inscriptions. Quintilian prefers a phonetically correct spelling rather than any attempts to go back to sources of earlier spelling (Ibid., I.7.31). He does, however, make conciliatory comments toward rigorous study of grammar and history, citing Cicero as a fine orator and grammarian (Ibid., I.7.34).