Note 438 — Chapter IV · PARMENIDES OF ELEA
Reading edition
I take πάντων as neuter and understand παλίντροπος κέλευθος as equivalent to the ὁδὸς ἄνω κάτω of Herakleitos. I do not think it has anything to do with the παλίντονος (or παλίντροπος) ἁρμονίη. See Chap. III. p. 150, n. 347.