Each soul is born with a purpose. To fulfil its true potential. To do this, it must evolve and move back to its source, it will strive to reunite with its maker!
To achieve this purpose the soul must grow and evolve, become aware and enlightened. Growth comes through learning and learning comes through experience, so each soul develops a consciousness, which becomes the vehicle for all experience. In other words, the soul experiences, learns and grows through its consciousness.
At a certain point of maturity, the consciousness is set free - it is joined to the soul still, but it is set free so that it may experience and evolve, interact and grow using its own free will, feeding all information back to the soul. In this way the soul develops and grows also, thus in time fulfilling potential and achieving its purpose.
The consciousness may experience and learn in many ways. It is like the 'tortoise and the hare' story. There are quick ways and not so quick ways - but all are worthy, all are good. They are simply different.
For example, the consciousness may choose to experience in the more celestial realms, (angelic forms for instance), or choose one of the many other 'non-physical' realms where the fairies and nature spirits live. Or, it may choose another entirely different way - by incarnating into physical and non-physical form, such as the physical being, the human being, life on and around the earth planes.
This cycle of learning we call reincarnation. And when your wakeful consciousness joins this cycle you become subject to certain laws. One being that of repetition. You will know from school, that a good way of learning is to repeat something over and over again until you understand it properly, then with this new learning and awareness you can move onto something else. Well, this is a good way of achieving, and basically this is the crux of reincarnation. But it is not the only way to learn. However...
Every physical life (as you know it) starts with birth, through to maturity, through to death. At the point of physical birth, the wakeful consciousness enters the body and it is as if a veil has been drawn across the memory of everything that has gone before it. The part of the consciousness that is 'wakeful' and aware of its surroundings, (its new physical body, mum and dad... and later school, work, recreation and so on), will knowingly forget everything that has gone before, in order for it to learn and grow starting from scratch. It will experience, evolve and move (once again) from the 'not knowing' into the 'knowing', feeding information back to its 'higher' and overall consciousness and soul. The higher consciousness is ever aware, it contains the sum total of your knowledge and is connected to the soul and at one with all. But, as you live your lives, you (or most of you) are not particularly aware of your greater, higher consciousness, you are only aware of the bit that you know, such as the way you feel, how you react and the effort that it takes for you to live your life successfully. Then, as age moves on, you prepare for your death, and hope for the best, you hope that there is more to come. Most of you are only 'wakefully' aware of this much through your physical lives.