I'm still not sure I get it.

The Y in "you" (or anywhere, for that matter) can't be a dipthong all by itself, can it? A dipthong is a combination of two vowels to make a sound distinct from either one individually.

If I understand the last post correctly, the Y in "boy" would be a semi-vowel (a new term for me) since it glides (ditto) with the O. This is what I had originally been taught was a dipthong as in the OI in "boil."

So. The Y's in "boy," "toy," "boytoy" etc are, at best, "semi-vowels"? But if you had a gun to your head and absolutely had to choose between Vowel or Consonant, which would it be? I'm hoping for the latter but God knows I've had my world turned upside down before.

So sweat on the Y in "fly" and "brightly" and the rest. They're vowels without question or argument. (Right? Please?)

And, by a similar no-other-vowel-present rule I also learned back when "Elvis" meant Presley and not Costello, the M in "rhythm" is the second vowel of that word. Every syllable HAS TO have a vowel of some sort. Or, again, so I was taught...

Thanks mucho for all past and future enlightenment.