no descansaré hasta que llegue

[starorbit88]

Hi everyone, I came across this example sentence while doing my flash cards, so there's no additional context beyond what's inferred.

I'm confused why in this case the subjunctive is used. At first I figured it was third person, then seeing it was meant to still be 1st person, I wondered why it wasn't simply llego. I've considered that sometimes it's used when it's conveying uncertainty or is speculative, but that seemed at odds with the speaker's determined spirit. What am I missing? Thanks!

No descansaré hasta que llegue a la entraña de este asunto.

I won't rest until I get to the heart of this matter.

 

[Azarosa]

Es correcto; la preposición hasta seguida de la conjunción que reclama siempre el subjuntivo cuando el sentido es prospectivo (Trabajaré hasta que me canse; No volverá hasta que [no] te disculpes; decidió no volver a verlo hasta que no se disculpara).

 

[Lnewqban]

The second action (to rest) depends on the first one (to arrive), but both happen in the same time (past or future).

No descansé hasta que llegué.

 

[User With No Name]

And an explanation in English:

With some conjunctions (including "hasta que"), the subjunctive is used if the event in question hasn't happened yet. The phrase "pending actions" is often used to describe this construction.

It's only vaguely about "uncertainty," because the subjunctive is used even in clauses like "mañana cuando amanezca" ("when the sun comes up tomorrow), because tomorrow's sunrise hasn't happened yet (and not because anybody thinks it's not going to happen).

 

[starorbit88]

Thanks! Your three explanations worked together to cover it well. I should've realized that 'hasta que' works in this sense just as 'para que' does.

 

[Doraemon-]

No descansó hasta que llegó. Se utiliza el indicativo porque es un hecho cierto, al ser un hecho pasado.
No descansaré hasta que llegue. Se utiliza el subjuntivo al ser un hecho futuro, y por tanto, incierto, hipotético, una posibilidad no materializada. No se sabe si llegará, ni cuándo, es un subjuntivo "de libro": hasta que eso ocurra.

Sobre qué en persona está el verbo (hasta que llegue) pues pueden ser o la primera o la tercera. Es ambiguo sin contexto, puede ser por ejemplo no descansaré hasta que llegue a mi casa (o sea, yo) o no descansaré hasta que llegue (mi madre).