"I learnt with certainty that it is above all the Sufis who walk on the road of God; their life is the best life, their method the soundest method, their character the purest character; indeed, were the intellect of the intellectuals and the learning of the learned and the scholarship of the scholars, who are versed in the profundities of revealed truth, brought together in the attempt to improve the life and character of the mystics, they would find no way of doing so; for to the Sufis all movement and all rest, whether external or internal, brings illumination from the light of the lamp of prophetic revelation."
Al-Munqidh min al-dalal (The Deliverer from Error), Imam Abu Hamid al-Ghazzali (1058-1111).