I'm drawing another of my famous blanks here: Can you use the "not...but" construction with the copula ("ní...ach" rather than "níl...ach") if you want to say that "_____...is only _____?"

This is for something someone's asked for input on elsewhere, and I'm second-guessing myself, as usual!

Redwolf

Níl ionam ach seanfhear -> Ní [...?] mé ach seanfhear.

Hmm, don't think so.

Ní amháin go bhfuil cois an éin briste ach tá a sciathán gortaithe freisin.

The specific sentence sought is:

"A dream without discipline is only a fantasy."

Redwolf

This is my attempt at it -

Brionglóid gan araíonacht níl ann ach samhlaíocht amhain (is that any good?)

I think the usual construction would be

Níl i/sa....ach.....

so to use franc's suggestion

Níl sa bhriongloid gan araíonacht ach samhlaíocht.

Go raibh maith agaibh!

Does "brionglóid" need to be definite? Could it be "Níl i mbrionglóid gan araíonacht ach samhlaíocht"?

Redwolf

Araíonacht? why not "smacht", which is more common in my opinion?

_________________
Is fearr Gaeilg na Gaeltaċta ná Gaeilg ar biṫ eile
Agus is í Gaeilg Ġaoṫ Doḃair is binne

"Smacht" was my leaning as well (thought I'd also thought of "gan srian")

Redwolf

To be honest I don't know.
I can't think why either wouldn't do.
I would wait for more learned opinions on it.