You, that write, either follow tradition, or invent such fables as are congruous to themselves. If as poet you have to represent the renowned Achilles; let him be indefatigable, wrathful, inexorable, courageous, let him deny that laws were made for him, let him arrogate every thing to force of arms. Let Medea be fierce and untractable, Ino an object of pity, Ixion perfidious, Io wandering, Orestes in distress. If you offer to the stage any thing unattempted, and venture to form a new character; let it be preserved to the last such as it set out at the beginning, and be consistent with itself.
— Horace, “Ars Poetica