7712. 'And one will grope in the thick darkness' means the density of the falsity arising from evil. This is clear from the meaning of 'groping in thick darkness' as a situation in which falsities arising from evil are so dense that one cannot recognize anything true or good at all. And if one goes in search of it one is like a person who gropes in thick darkness, stumbling and colliding with objects everywhere. This is why in Isaiah 8:22 the thick darkness is called a thick darkness of colliding, described in the same prophet as follows,

We walk in thick darkness. We grope for the wall like the blind, and as if without eyes we grope; we stumble at midday as if it were twilight; among the living we are like the dead. Isaiah 59:9-10.