al-Maqsid al-asna fi sharh asma Allah al-husna (Min rawai hujjat al-Islam Abi Hamid al-Ghazzali)

Perhaps this excerpt from Al-Ghazali's 'Savior from Error' (al-Munqidh mina 'd-Dalal) Al-Baz Publishing, will help: "From the start of the Spiritual Path, the sufis begin to experience visions and mystical disclosures, to the point where, in their wakefulness, they witness the angels and the spirits of the Prophets, as well as hearing their voices and obtaining benefits from them. The situation then progresses from the witnessing of forms and likenesses, until it reaches levels that cannot be described in words, so anyone who attempts to define them runs the risk of patent error. Generally speaking, the matter results in a nearness [to the Lord], which amounts to incarnation [Hulull] according to the fantastic notion of one sect, unification [ittihad] according to another, and integration [wusul] according to yet another. All these ideas are erroneous, and we have explained the nature of the error in the book entitledal-Maqsid al-Asna [The Loftiest Goal]. If someone is confused about that, he should simply say [quoting the words of the poet]: It was as it was, though I cannot explain it, so think the best and ask no more about it! The gist of the matter is this: If someone has no understanding derived from experience, the reality of Prophethood is beyond his comprehension, apart from the name. The charismatic talents of the saints are actually the initial stages of the Prophets.