Or [do they think] that the hidden reality [of all that exists] is within their grasp, so that [in time] they can write it down?

Or that the Unseen is in their hands, so that they can write it down?

Or is the Unseen theirs that they can write (thereof)?

Or is the unseen with them so that they write (it) down?

Or have they [knowledge of] the unseen, so they write [it] down?