The effect of death on the composite nature of man is as follows:
Man has two souls, an animal soul and a spiritual soul, which latter is of angelic nature. The seat of the animal soul is the heart, from which this soul issues like a subtle vapour and pervades all the members of the body, giving the power of sight to the eye, the power of hearing to the ear, and to every member the faculty of performing its own appropriate functions.
It may be compared to a lamp carried about within a cottage, the light of which falls upon the walls wherever it goes. The heart is the wick of this lamp, and when the supply of oil is cut off for any reason, the lamp dies. Such is the death of the animal soul.
With the spiritual or human soul, the case is different. It is indivisible, and by it man knows God. It is, so to speak, the rider of the animal soul, and when that perishes it still remains, but is like a horseman who has been dismounted, or like a hunter who has lost his weapons. That steed and those weapons were granted the human soul that by means of them it might pursue and capture the Phoenix of the love and knowledge of God.
If it has effected that capture, it is not grief but rather a relief to be able to lay those weapons aside, and to dismount from that weary steed. Therefore the Prophet said, “Death is a welcome gift of God to the believer.”
But alas for that soul which loses its steed and hunting-weapons before it has captured the prize! Its misery and regret will be indescribable.
Al-Ghazzali, The Alchemy of Happiness.
The influence of Al-Ghazzali upon both the Christian and Islamic thinkers of the Middle Ages and beyond is being more and more widely documented. Known as the Proof of Islam, Ghazzali finally won acceptance for Sufism in Islam.
Above all, Ghazzali was a Sufi, and The Alchemy of Happiness is his own abridgement, designed for the ordinary reader, of his colossal master-work, The Revival of Religious Sciences.