In Numbers 31:5, Numbers 32:17, this signifies prepared to accept knowledges of truth. (Apocalypse Explained 430[11])

(Reference: Arcana Coelestia 2162; Daniel 10:6)

232. The situation today is far worse than it was in the past, since people are now able to confirm their incredulity of the senses by means of facts that were unknown to the ancients. The thick darkness that results is so great that it defies description. If man knew how great that thick darkness really was he would be dumbfounded.