E. Christian Kopff
The race at Aristotle, Rhetoric 3. 9 is usually taken as a stadion. Interpreting it as a diaulos brings it in line with Aristotle’s doctrine of the period and a slight emendation contrasts the two laps.
At Rhetoric 3.9 Aristotle contrasts the periodic style with what he calls “strung-on” or “continuous.” “I call that strung-on which has no end in itself except in so far as the thought is completed. It is unpleasant because it is unlimited, for all wish to foresee the end. Thus, as they complete the course [runners] pant and are exhausted; for they do not tire while the goal is in sight ahead.” (Kennedy, 1991)
Most commentators and translators take the race in the simile to be the stadion, a one lap race in a straight line, but the diaulos, or two lap race with a clear marker in the middle, fits Aristotle’s doctrine of the period, which has two cola: “A colon is one of two parts of a period.” (1409b16). Demetrius, De elocutione 34 understood this: “This definition means that the period is of cola, obviously.” Walter Schmidt cited Aeschylus, Agamemnon 344: “to round in due course the bend of the racecourse.” (Lloyd-Jones). Demetrius, De elocutione 11 uses a diaulos simile to illustrate Aristotle’s definition of a period. Although Aristotle once (1409b20) mentions “the period with one colon,” he compares the period to strophe and antistrophe in lyric poetry (1409a24-26). At 1409b33-1410a35 he quotes a score of examples, all of two cola. Kennedy, 1958 explains Aristotle’s term for “periodic,” katestrammene: “It is that which has been turned over, around or back. Of a sentence it would mean a statement which goes one way and then comes back again in a twofold motion.” By “period,” Gotoff explains, “What Aristotle was referring to, I think, was a sentence the structure of which could be reduced to a pair of discrete units ....This view, perhaps, makes sense of the metaphor of the race track in which the runner would start out, say, on a hosper-clause, round the post, and return with the houtos-clause.” Fleming notes, "The diaulos seems tailor-made to illustrate an antithetical 'period'." Most commentators and translators, Cope, Jebb, Freese, Wilkinson, Fowler, the Budé editors, disagree, but interpreting the race as a diaulos is supported by several considerations.
(1) The runners pant and collapse at the kampteres, which, “properly the turning point of the diaulos or double course, is here used for the goal itself.” Freese) LSJ, s.v. II, shows how the word developed from “turning point of the double lap race” to “goal of the single lap race.” The context here favors contrasting kampteres and peras.
(2) Compare the race simile in Aristotle, NE 1.4.1095b1: “Plato, too, was right in raising this question and asking, as he used to do, ‘are we on the way from or to the first principles?’ There is a difference, as there is in a racecourse between the course from the judges to the turning -point and the way back.” (Ross) The point of Plato's simile depends on the fact that the two laps are run in different fashions.
(3) gar is confusing. The fact that a runner is not tired before does not explain why he is tired now. The simile calls for a contrast between an unpleasant situation where the final goal is not in view and a pleasant situation where the goal is in sight. The intrusive gloss gar for de is a common slip, e.g. Pindar, Olympians 2.22. It is sometimes correct (Denniston, 169-170), but not here. The needed contrast is given by de.
I would translate: “Everyone wants to see the goal clearly. That is why the armed runners are panting and collapsing at the mid-point of the race, but (de), when they see the goal in front of them, they have no trouble in running ahead.”