by Imam Al-Ghazzali (Author), Claud Field (Translator)

God has sent on earth a hundred and twenty-four thousand prophets to teach men the prescription of this alchemy, and how to purify their hearts from baser qualities in the crucible of abstinence. This alchemy may be briefly described as turning away from the world to God, and its constituents are four: 1. The knowledge of self. 2. The knowledge of God. 3. The knowledge of this world as it really is. 4. The knowledge of the next world as it really is. We shall now proceed to expound these four constituents in order.