What is the English translation of "quizá el de qué..."?

Question

For context, the full sentence I am trying to understand is "Su vida de ermitaño era un enigma, quizá el de qué secretos ocultaba, cómo podía haber vivido seis décadas sin desafíos notables."

I understand most of the sentence - my rough translation is "His life as a hermit was an engima, ..., how he had been able to live six decades without notable challenges." It's the middle part that is confusing me. "Maybe what secrets were hidden/he hid" is the best I can come up with, but that doesn't seem to make much sense. How would this segment translate into English?

Answer 1

"Su vida de ermitaño era un enigma, quizá el de qué secretos ocultaba, cómo podía haber vivido seis décadas sin desafíos notables."

In the comment «quizá el de qué secretos ocultaba», the article el stands for el enigma. This is a type of nominal ellipsis. The article refers to the noun enigma that has just been mentioned:

...un enigma, quizá el enigma de qué secretos ocultaba...

It's basically the same as in English, if you allow for that el being translated as "the one".

Note that enigma is masculine; that's why you use el in the ellipsis. If you want to drop a feminine noun, you must use la instead (and you must of course use los or las if the noun is plural, masculine o feminine respectively).

The rest of the phrase («...de qué secretos ocultaba») is subordinated to that elliptic el (meaning el enigma). So the whole means "...an enigma, the one (=the enigma) of what secrets he was hiding".

There seems to be an unspoken "or" as well; the enigma was maybe (quizá) the secrets he was hiding or (else) how he could have lived... etc.