The Tasawuf of gnosis or inner knowledge is a very difficult path. According to some texts the aspect of 'ma'rifa' (knowledge) was introduced into Tasawuf by Dhu-l-Nun of Egypt, but actually this aspect already existed in the earlier scriptures. The direct research of knowledge is not recommended for everybody. This knowledge cannot be acquired; it comes by itself only when the aspirant is ready. 'Riazat' (asceticism), 'khid-mat-e khalq' (karma yoga) and other spiritual practices prepare the heart to become the temple of this knowledge. According to Ustad-e Imam Abu-al-Qasem Hawazan-al Qushaiiri, ma'rifa comes into the the heart from God when the mystic has stilled all the notions of his mind. This knowledge is spiritual discrimination (gyana) and in the sufi conception it encompasses all knowledge. This given, but not acquired, knowledge is called 'elm-e ladonni' and some great masters have had it by birth or by self-realization.
One of the greatest masters of gnosis is Hujjut-ul-Islam Imam Abu-Hamed Mohammad-e Tusi, famous as al-Ghazzaii (the spinner) who lived from 1059 to 1111. A clever, ambitious and egoistic child, he decided to become the greatest authority of Islamic theology. Indeed, mastering all scholasticism, knowing about 300,000 traditions (hadith) of the Prophet by heart, by the age of 35, he became Hujjat-ul-Islam (the authority or the proof of Islam, the highest academic title of his time). He was a great thinker who saved Islamic thought from decay. He was rector of the famous Academy of Baghdad (Nizamiyah) and in his daily lectures on divinity more than 4,000 scientists, scholars and great philosophers were usually present from all over the world and from all religions and ideologies. However, just at the time when his methodology had been accepted by Islamic, Christian and Jewish scholars alike, he became sceptical of the power of pure canonic law to guide man to awareness and realization and felt a yearning for more personal experience of God. Without even a brief explanation he left the Academy and began wandering and observing the world 'unknowingly.
In his autobiography he writes: "When I first turned my attention to the way of the sufis, I knew that it could not be traversed to the end without both doctrine and practice. The doctrine was easier to me than the practice so I began learning it from the books and sayings. When I had learned as much as possible I clearly saw that what is most peculiar to the sufis cannot be learned but can only be reached by immediate experience, ecstasy and inner transformation. I became convinced that I had now acquired all the knowledge of sufism that could possibly be obtained by studying, and there was no way of coming to the rest except by leading the mystical life. I saw myself as I was - worldly interests encompassed me on every side. Even my work as a teacher, the best thing I was engaged in, seemed unimportant and useless in view of the life hereafter. When I considered the intention of my teaching, I perceived that instead of doing it for God's sake alone, I had no motive but the desire for glory and reputation. I realized that I stood on the edge of a precipice and would fall unless I set about to mend my ways......Conscious of my helplessness and having surrendered my will entirely, I took refuge with God as a man in sore trouble, who has no resource left. God answered my prayer and made it easy for me to turn my back on reputation and wealth, wife, children and friends."
Arriving in Tripoli, Ghazzali worked as a sweeper in a theological school to support himself, being happy with his success in commanding his 'commanding self'. One morning, sweeping a veranda, he heard two scholars discussing a philosophical question heatedly. It ended with one telling the other, 'This is not my own conclusion, but our master Ghazzali has said it'. The second student accepted without discussing any further. Ghazzali was surprised to see the power of his name in a far off country and suddenly he perceived that the 'commanding self from which he was a refugee was always and everywhere with him still.
"When even a finest particle of your individuality remains
The bazar and shop of egoism remains
You say, 'I broke the idol of illusion, I am saved'
When what really remains is the idol of being
Devoid of illusion."Sheik Ahmad-e Jam
After ten years of wandering and observation, during which he attained the highest state of enlightenment, Ghazzali returned to Tus, his native village in north eastern Iran, where he wrote his great treatise 'Ehia'ul-ulam' (Revival of Knowledge). He also wrote a summary of this massive work in Persian which is entitled 'Alchemy of Happiness'. This text is readily available and more comprehensible for the beginning aspirant on the path of knowledge. Ghazzali can perhaps be considered the Shankaracharya of Erfan. His chief work 'Ehia'ul-ulam' is surely one of the most systematic treatises concerning spiritual discrimination.