Learn Italian: Non so se la mente possa concepire l'oscurità oltre le stelle. - I do not know if the mind can conceive the darkness beyond the stars.

The phrase Non so se introduces an indirect question (a question embedded inside a statement). Because non so expresses doubt and uncertainty, it triggers the subjunctive in the dependent clause. Using possa highlights that the mind's ability to do this is a theoretical or uncertain possibility.

Is it strictly wrong to use the indicative (può) in an indirect question like this?

No, it is not wrong. In everyday spoken Italian, you will very often hear people use the indicative for indirect questions (for example, Non so se la mente può...). However, using the subjunctive (possa) elevates the register, making the sentence sound more formal, literary, or philosophical, which perfectly fits the poetic tone of this sentence.

I have seen oltre followed by the preposition a, like in oltre a questo. Why is it just oltre le stelle here?

When oltre is used in a physical, spatial, or figurative sense to mean 'beyond' or 'past' a certain limit, it connects directly to the noun (oltre le stelle). It is generally followed by a when it means 'besides' or 'in addition to' (like oltre a questo, meaning 'besides this').

How does concepire differ from a more common verb like capire here?