Dreams are important, because they believe that true reality, is in fact in the dream world, not the world we inhabit. They speak of a primordial time in the history of the entire universe as the "dream time," when everything was created. The dream world, is in fact, the spirit world, and ultimately all living creatures return to the world of dreams. The aborigines believe, the dream world is what confers upon human beings, their various gifts, or curses, and to know how to cross over into it, one can ask from it favors, and manipulate it in some form or other.
To the aborigines, good dreams are seen as a blessing upon an individual, while bad dreams of course are a bad omen. Bad dreams are a bad omen, because it means the person's own inner spiritual poison, prevents them from experiencing the true nature of the dream world. See, if a person is spiritually pure, every time they dream, they can see paradise. You wake up more well rested than with normal sleep, and you can even learn, acquire knowledge if you wish. If a person is spiritually impure, then nightmares will be frequent, and often horrifying. While Islam holds such dreams come from the Shaitan (the devil), Hebrew lore, from demons, the Aborigines hold, its all you; YOU, are the cause of your own nightmares, not the devil, or groups of devils, it is the the evil within you. Buddhists, on this point at least, would agree with Australian Aborigines; Buddhism sees nigthmares as a) memories from past lives or b) very bad Karma, manifesting itself as negative images within the mind. The Aborigines see bad dreams as a very bad sign, it means that your soul is full of corruption. Buddhists call it Karma, the aborigines see it, as spiritual poison, the result of a person disconnecting themselves from the spirit world. Their whole spiritual belief system, revolves around it.