Is this sentence grammatically correct or incorrect?

[David Jo]

What the exact mix of experience and natural talent that made Austen the brilliant writer she was may never be unknown.

I think another 'was' should be put in between was and may, or 'she' must be left out. Maybe I was wrong. If incorrect, would you explain why?
Some argue that the clause introduced by what in the subject position is a kind of structure from an exclamation sentence like "What a pretty girl she is!." Can it be possible that an exclamation sentence constitutes a subordinate clause serving as a subject in the main clause?


Can you also paraphrase the sentence in plain English for non native speakers like me to catch the meaning (connotation), more easily?
Especially the meaning of the word 'mix' seems to be elusive.

[Lucretia]

Hello David Jo,

To my mind, something is surely missing in the sentence – you might have miscopied it. I can’t make head or tail of it; it doesn’t make sense at all.

[David Jo]

Hello David Jo,

To my mind, something is surely missing in the sentence – you might have miscopied it. I can’t make head or tail of it; it doesn’t make sense at all.


Sorry, but I didn't miscopied it at all. I double checked it. It's the exact text from the magazine Journal.
Anyway, you mean the sentence is wrong because somthing is missing? If that's the case, What is it that is surely missing?

Thanks anyway!

[Rusty]

"What the exact mix of experience and natural talent that made Austen the brilliant writer she was was may never be unknown."
The added "was" fixes the grammar, but the sentence is rather awkward, isn't it?
I'd reconstruct it this way:
What the exact mix of experience and natural talent was that made Austen the brilliant writer she was, may never be known.
Or simply:
The exact mix of experience and natural talent that made Austen a brilliant writer may never be known.

[David Jo]

Thanks so much!!!! Rusty
That's the very answer I wanted.