The Sign of a Dead Heart [Hikam 48]

"A sign of the heart's death is the absence of sadness over the acts of obedience that you have neglected and the abandonment of regret over the mistakes that you have made" What is a living heart and what is a dead heart? What causes the heart to spiritually die and what factors enliven it? The following talk expounds with great detail the famous narration of the Prophet (Allah bless him and grant him peace) "the similitude of the one who remembers his Lord and the one who does not is like that of the living and the dead".