never understanding … never perceiving: The prophet's words revealed the true feelings of his audience. The people were so deep in sin that hearing the truth pushed them further from God instead of closer (for example, Ahaz, Isaiah 7). Yet, the truth needed to be spoken.
Jesus also used this principle in his own preaching (Matthew 13:14–15; Luke 8:10; 19:42; John 12:40; see also Acts 28:26–27; Romans 11:8).