One of the primary necessities of a rebirth process that involves the soul’s transit to the mental, vital or spiritual worlds, is just the fact of the inter-relationship between these worlds and the manifestation of their powers within the physical universe. There is a natural pull that these worlds exercise on the corresponding elements in the human personality, which, when they are freed from the limits of the physical earthly body, would naturally incline them to return to their own native sphere, there to assimilate the experience and prepare for the next stage.
Sri Aurobindo points out that in the rudimentary stages of human development there may be a counter-acting pull back into the earthly life, either through a strong preponderance of affinity with the physical nature, or through a strong urge of unfulfilled desire. These counter-acting weights might cause the soul to reincarnate immediately after the death of the body without visiting the vital, mental or spiritual worlds. But these forces eventually are overcome by the influence and higher power of the evolved vital, mental & spiritual worlds, eventually leading to the necessity described above of an interlude for the soul to escape from earthly life, move in the native atmosphere of one of the higher worlds, assimilate experience and prepare for a new formation and personality to extend the evolution of the soul in the next round of rebirth.
Sri Aurobindo, The Life Divine, Book 2, Part 2, Chapter 22, Rebirth and Other Worlds; Karma, the Soul and Immortality