Hermogenes of Tarsus (2nd century AD) and his treatise On Types of Style (Peri Ideōn). He analyzed oratory into seven “ideas” or qualities of style.
Hermogenes treated these as ideal qualities that a speaker mixes in different proportions rather than as seven mutually exclusive “modes.” They are:
- Clarity (saphēneia) — the foundation. Speech must be intelligible first.
- Grandeur (megethos) — elevation, dignity, majesty. Used for weighty subjects, moral exhortation, or public crisis. Subdivided into solemnity, brilliance, asperity, vehemence, abundance, etc.
- Beauty (kallos) — elegance, harmony of rhythm and structure, aesthetic pleasure.
- Rapidity (gorgotēs) — speed, concision, liveliness; keeps the audience from growing bored.
- Ethos / Character (ēthos) — the moral and personal color of the speaker. Language that reveals (or constructs) trustworthiness, temperament, and values. Closely related to Aristotle’s ethos.
- Sincerity / Verity (alētheia) — the impression of speaking from genuine feeling or conviction rather than artifice.
- Force (deinotēs) — the culminating quality: the powerful, appropriate combination of the previous six. Some Renaissance commentators called this “Gravity” or associated it with decorum.
Hermogenes regarded Demosthenes as the supreme model because he could deploy all of them in the right measure.
Relation to the seven planets
Classical Greek sources do not assign these seven rhetorical styles to the seven planets. That linkage is a later (often Renaissance or esoteric) overlay.
What is ancient is the habit of mapping other sevens onto the planets:
- The seven Greek vowels (Α Ε Η Ι Ο Υ Ω) were frequently given planetary correspondences (Plutarch, Nicomachus, the Greek Magical Papyri).
- The seven musical harmoniai / modes were likewise associated with planets in some Pythagorean and later astrological-musical schemes.
Someone combining Hermogenes’ seven stylistic “ideas” with the planetary week or the harmony of the spheres is an attractive synthesis, but it is not a doctrine you will find in Hermogenes himself or in the earlier rhetorical tradition (Aristotle, Theophrastus, Dionysius of Halicarnassus, Cicero, Quintilian). Those authors work with three main stylistic levels (grand, middle, plain) plus the virtue of to prepon / decorum (appropriateness to subject, audience, and speaker).