φημὶ τοίνυν τὸν ἄριστα ἱστορίαν συγγράφοντα δύο μὲν ταῦτα κορυφαιότατα οἴκοθεν ἔχοντα ἥκειν, σύνεσίν τε πολιτικὴν καὶ
δύναμιν ἑρμηνευτικήν, τὴν μὲν ἀδίδακτόν τι τῆς φύσεως δῶρον,
ἡ δύναμις δὲ πολλῇ τῇ ἀσκήσει καὶ συνεχεῖ τῷ πόνῳ
καὶ ζήλῳ τῶν ἀρχαίων προσγεγενημένη ἔστω.
I say, therefore, that he who would write history well must be possessed of these two principal qualifications, a fine understanding and a good style: one is the gift of nature, and cannot be taught; the other may be acquired by frequent exercise, perpetual labour and an emulation of the ancients.
Lucian, “How to Write History,” 59.34 (tr. T. Francklin, 1780).