>A schwa is _mid_ (not
> front like [E] as in "pet" nor back like [O] as in "pour") and _central_
> (not high like [i] nor low like [u]). It is completely non-peripheral. It
> is not "front" in any way, otherwise it wouldn't be a schwa!
Steady on there! You are right, the vowel we name "schwa" is as you
describe, but not all neutral vowels are "schwa", and the vowel we call
"schwa" in PIE might well have been forward or higher or more rounded than
the IPA schwa, and still have been a neutral minimal vowel.
The modern French neutral "schwa" (as in "le" etc) is rounded and slighter
more fronted than English. There are regional variations which also prove
my point. The German neutral vowel as in the last syllable of "Name, sehe"
etc) is considerably more fronted than the English, and in the south it is
also rather higher.
Peter