In one aspect the dream is the exact picture of reality which one may sooner or later experience in his so-called real life. This again teaches the fact that the incidents which we experience unexpectedly in life were pre-ordained for us. It also teaches us that here in the physical plane though we appear to be one separate from the other, in the plane of the dream upon the surface of the individual's mind the whole world exists. He who is one single being in the physical plane, inverts into the whole world in the plane of the dream, although he holds still fast his individuality even there where he is alone.

The second aspect of the dream has the opposite nature of manifestation as everything in it appears to be the reverse to what may be going to happen. For instance a person seen dead in a dream will have a long life, and the sickness of a friend seen in a dream would on the contrary bring him good health. It is because of its negative nature everything, either the printer's block, the photographic plate, the humorous glass and all things of a negative character will show opposite before they manifest aright.

The third aspect of the dream is of little importance, just like the birth of a child who after living only a week, has died. The same is the case with the dreams produced before the view of man either caused by the unbalanced activity of mind or by the disorder of the health. Such dreams have as a rule no importance, and they are surely a waste although they create before man a moving picture.

The first aspect of dreams is generally manifest to the spiritual person, of course seldom they are noticed also by the average man.
The next aspect of the dream generally manifests before the view of those who possess the attribute of humanity, who first think of the world and its responsibilities, together with the thought of God.
The third aspect of the dream is vouchsafed to each person in his every day life, caused by the activity of his mind.

A dream is an inspiration, according to the point of view of the Sufi. There are four kinds of dreams.

The soul dream. That dream is the actual vision of something that has passed, or that is going to happen, or that will happen.
The heart dream. In this dream there is a feeling more dominant than when one sees. The feeling itself is expressive of what has happened or will happen.
The symbolical dream, the mind dream. This dream comes to a man of artistic mind or mystical spirit, when, in the language of dreams, so to speak, he knows the past, present and future.
The dream of the mind. Whatever the mind is impressed with during the day, the mind goes on repeating it, and the dream is the same kind of impression.

Every person has that kind of dream, either clear or confused. But the mystical artist dreams the dream which is symbolical. The dream of a person who is tender, kind and sympathetic [is the heart dream]. The soul dream comes to a spiritual person. At the same time to some persons some of those four dreams happen, or each of these dreams may be manifested to him.

If I were to define the cause of dreams it would take perhaps a long time, but what I mean to say just now is, that

according to the state of man's spiritual development he receives the knowledge of the unseen world.