Sufism, despite having many definitions, is indefinable in itself: it cannot be closed in a static category. A master’s answer to the question «What is Sufism? » could be the history of the Elephant in the darkness.

Inside a room, dark as pitch, a huge elephant was lying asleep. A group of people, who never heard in their lives about an animal like it, should discover what the “mysterious object” was. Since darkness avoided its shape distinguishing, they touched the animal to make up their own idea. The first one touched the pachyderm’s leg and said: “Sure, it’s simple, it is a huge column!”.  
The second one, who touched its ear, exclaimed:
“But what are you saying, it is for sure an enormous fan!”.
The third one, who took its trunk, stated:
“But are you crazy? How can it be what you’re saying? It’s certainly a snake!”.
The one who seized its back declared:
“I think you cannot see straight, how can’t you see it’s a big throne?”
The one who touched its head said:
“I do not agree with none of you, this object is a boiler, no doubts!”.
And so on. Since everyone’s opinion was based on a fragmentary experience, they found many different definitions, as many as the pachyderm’s parts that were touched. Each one believed having found out what the object was. And, since everyone supported his own opinion, they began quarrelling animatedly.
“The mysterious object resembles to this!”.
“No, to this!”.
“It does not resemble to this, but to that!”.
But when a lantern was lighted up in the room, they could see the whole animal and they understood that everyone got only a partial truth, confusing it with the whole one. The same happens to those who try to explain what Sufism is: each one tries to explain his own feelings.

Sufism is not a religion, nor an abstract thought, apart from life. It does not want to systematize knowledge, it does not deny the other conceptions. It does not stress on books or beliefs, but on experiences man can make in his everyday life. That’s why they say Sufism is “being within the world, but not of the world”, since it talks to the ones who, even though they are busy with everyday tasks, are not kept imprisoned by them.
Sufism, after searching in the real essence of religion, rejects its unessential aspects. It is a concrete way of conceiving life, an eye that sees the real world as an awakening. It is a mental training method within the adventure of life. 

According to the ones who appreciate its atemporality, Sufism is a real and flourishing reality long before Mahomet teaching, always existing in any time; according to others, it is Islam’s medulla; anyway, Sufism  allows man to fulfil the Divine that lives inside his own heart and to live in a perfect adherence to the present instant. 

Sufism needs the exam, the study, the observation of the human condition and the direct and practical experience of these phenomena. It stresses on practice, since a philosophical thought cannot be parted from everyday life. This would be like pulling up a plant from the ground. Once the roots are pulled up, life goes away. Sufism turns around the matter of transformation: to transform the world of appearances into an extraordinary world, filled up by the meaning of Divine.
That’s also why a famous Sufi saying says «The one who tastes, knows».