The same misconception exists among those who believe that the heart feels. The heart, being the center of the body, partakes of the effect of the feeling from within - which is the real heart, not the piece of flesh - and it feels suffocated and oppressed. Depression is felt as a heavy load upon the breast; and when the heavy vibrations are cleared, then especially a person has a feeling of joy and his heart is lighter than usual. This explains the Shaqq-i sadr, the opening of Muhammad's breast by the angels when fear, bloom, bitterness, and conceit were all cleared away before the manifestation of divine revelation. It is as the darkness clearing away at the rising of the sun.