The soul is the light / energy that resides within us and it continues on a journey through many physical bodies. The soul is eternal. Reincarnation is the process of the soul changing from its old physical body to its new one. This physical body can be animal or human; the human form is the highest form a soul can be born in. The soul does not actually die, nor is it reborn, it simply changes body. When a new soul is brought to life, it is actually a tiny spec of light split off from the cosmic light and as such is and stays part of it. This tiny spec of light will grow during hundreds of human (or animal) lives. The journey of the soul takes the form of each physical reincarnation.  Just like we change clothes, the soul takes on different bodies to learn various lessons.