In such a context, their means of communication would likely be inscrutably advanced, as distant from our radio waves as a symphony is from a lone drumbeat.
Crookshanks wandered over to them, leapt lightly into an empty chair, and stared inscrutably at Harry, rather as Hermione might look if she knew they weren't doing their homework properly.
She viewed literature much as she did Providence, as an inscrutably mystery; and she spoke of Howland as a dedicated being, set apart to perform secret rites within the veil of the sanctuary.