Laudator Temporis Acti

Rudolph Pfeiffer (1889-1979), History of Classical Scholarship from the Beginnings to the End of the Hellenistic Age (Oxford: Clarendon Press, 1968), p. 207:

The complete repertories were called πίνακες (indexes); but there was no corresponding Greek or Latin word for the selective lists. In the year A.D. 1768 the term 'canon' was coined for them by David Ruhnken,¹ when he wrote: 'Ex magna oratorum copia tamquam in canonem decem dumtaxat rettulerunt' (sc. Aristarchus et Aristophanes Byzantius). Then Ruhnken dropped the cautious 'tamquam' and went on calling all the selective lists 'canones'. His coinage met with worldwide and lasting success, as the term was found to be so convenient; one has the impression that most people who use it believe that this usage is of Greek origin. But κανών² was never used in this sense, nor would this have been possible. From its frequent use in ethics κανών always retained the meaning of rule or model. Aristophanes' grammatical observations about analogy in declension could be called κανόνες, rules, or a certain author and his style could be described as κανών, a model or exemplar.³ So it was not by the ancient, but it could have been by the Biblical, tradition that the catachrestic use of canon was suggested to Ruhnken. Though the Biblical canon does not mean a list of writers, it does mean a list of books of the Bible accepted by the Christian church as genuine and inspired;⁴ and this usage was and is current in all the modern languages. The word 'canon' has been intentionally avoided in this chapter on Aristophanes; nevertheless, everyone is at liberty to speak of the Alexandrian canon of the nine lyric poets or the ten orators, since the expression is sanctioned by its age and convenience, and will, I am afraid, never disappear. But if one calls such lists 'canons', one should be aware that this is not the proper significance of the Greek κανών but a modern catachresis that originated in the eighteenth century.

¹ D. Ruhnken, 'Historia critica oratorum Graecorum' in his edition of Rutilius Lupus 1768 and often reprinted: Opuscula I² (1823) 386.
² H. Oppel, 'Κανών. Zur Bedeutungsgeschichte des Wortes und seiner lateinischen Entsprechungen (regula-norma)' Philologus, Suppl. xxx 4 (1937) passim; on Ruhnken see p. 47. Cf. the review by K. v. Fritz, AJP 60 (1939) 112 ff.
³ See above, p. 202 (declension) and p. 206, n. 2 (Aeschines' λόγοι as κανών).
⁴ Euseb. hist. eccl. VI 25. 3 τὸν ἐκκλησιαστικὸν φυλάττων κανόνα, μόνα τέσσαρα εἰδέναι εὐαγγέλια μαρτύρεται (sc. Origen) seems to be the earliest evidence of the word for the canon of scripture; Oppel Κανών 70 f. and others refer to a passage of Athanasius, written about A.D. 350, at least twenty-five years after Euseb. hist. eccl., Athanas. 'de decr. Nic. syn.' 18 (Werke, hg. von der Preuß. Akad. d. Wiss. II 1, 1935, p. 15. 20) μὴ ὂν ἐκ τοῦ κανόνος (sc. Hermas).