From Bhikkhu Bodhi's notes on the Chariot simile.
Spk: The eightfold path is called
the straight way (
ujuko maggo) because it is devoid of crookedness of bodily conduct, etc. The destination, Nibbana, is said to be
fearless (
abhaya) because there is nothing to fear in that and because there is no fear for one who has attained it. Unlike an actual chariot, which rattles or whines when its axle is not lubricated or when it is mounted by too many people, the eightfold path does not rattle or whine. (
na kujati na viravati) even when mounted simultaneously by 84,000 beings. The chariot itself is also the eightfold path, and its
wheels of wholesome states (
dhammacakka) are bodily and mental energy. the D'hamma" that is called
the charioteer is the supramundane path, with the
right view of insight (
vipassana-sammaditthi)
running out in front (
purejava). For just as the king's servants first clear the path before the king comes out, so the right view of insight clears the way by contemplating the aggregates, etc, as impermanent, etcd, and the right view of the path (
magga-samma-ditthi) arises fully understanding the round of existence.
The extended simile should be compared with that of the
brahmayana, the divine vehicle, at SN 45.4; see too the extended chariot simile at Ja VI 252-53.
SN 45.4 is at:
http://www.metta.lk/tipitaka/2Sutta-Pit ... ggo-e.html44. 1. 4. (4) Bràhmano (The numbering system is different in that translation from Bhikkhu Bodhi's).