Sufism is a school for the actualization of divine ethics. It involves an enlightened inner being, not intellectual proof; revelation and witnessing, not logic.
By divine ethics, we are referring to ethics that transcend mere social convention, a way of being that is the actualization of the attributes of God.
To explain the Truth is indeed a difficult task. Words, being limited, can never really express the perfection of the Absolute, the Unbound. Thus, for those who are imperfect, words create doubt and misunderstanding. Yet:
If one cannot drink up the entire ocean,
one can drink to one's limit.
Philosophers have written volumes and spoken endlessly of the Truth, but somehow their efforts have always fallen short. For the sufi, philosophers are those who view the Perfection of the Absolute from a limited perspective; so all they see is part of the Absolute, not the Infinite in its entirety. It is indeed true that what philosophers see is correct; nevertheless, it is only a part of the whole.
One is reminded of Rumi's well-known story of a group of men in India who had never seen an elephant. One day they came to a place where an elephant was. In complete darkness they approached the animal, each man feeling it. Afterwards, they described what they thought they had perceived. Of course their descriptions were different. The one who felt a leg, imagined the elephant to be a pillar. The one who felt the animal's ear, described the elephant as a fan, and so on. Each one of their descriptions with respect to the various parts they had experienced was true. However, as far as accurately describing the whole, their conceptions had all fallen short. If they had had a candle, the difference of opinions would not have come about. The candle's light would have revealed the elephant as a whole.
Only by the light of the Spiritual Path and the mystic way can the Truth be discovered. In order for one to truly witness the Perfection of the Absolute, one must see with one's inner being, which perceives the whole of Reality. This witnessing happens when one becomes perfect, losing one's (partial) existence in the Whole. If the Whole is likened to the Ocean, and the part to a drop, the sufi says that witnessing the Ocean with the eye of a drop is impossible. However, when the drop becomes one with the Ocean, it sees the Ocean with the eye of the Ocean.