>Why Grassmann's law didn't take place in Greek word Phaethon? Why not
Paethon?
Influence of root Pha- ?
Grassmann's Law does not operate consistently, and it does not operate
equally over different boundaries.
(a) It does operate fairly consistently when stems are formed from roots
(e.g. the perfect formations).
(b) It normally operates over inflexion endings, but not always.
(c) It operates less commonly over morpheme boundaries (so we have some
famous inconsistencies).
(d) It very seldom operates over a distance. Even two vowels instead of one
can prevent its operation.
So the answer depends on how you think Phaethon is formed. We wouldn't
normally expect Grassmann's law to operate at a distance of two syllables
(-ae-), but there are alleged cases where it might be happening.
Peter