There are various layers of the cosmos, just as there are layers of the individual inside. We call them - the physical sheath, the vital sheath, the mental sheath, the intellectual sheath and the casual sheath. Corresponding to these sheaths there are the planes of existence - outwardly, cosmically, universally - and these are the regions into which the soul enters as a citizen thereof. Rebirth need not necessarily mean coming back to this world. Rebirth is a compulsion to take a form and the inability to exist as the formless Absolute. The necessity to enter into a form arises on account of the impulsions of desire which are the forces that constitute the individuality of a person. A desire is a power or force which asserts the need to retain individuality in some manner or other. The individuality need not necessarily be of a physical type. There are various degrees of individuality - nevertheless they are individualities, and the degrees vary according to the degree of the particular plane of existence into which the individual is thrown by the power of the evolutionary process itself, which is called rebirth. So rebirth is not necessarily a coming back to this world. It may be that, or it may not be that. It can be a higher ascent also, but even then it is rebirth. Anything is rebirth if it is short of God-realisation, Even if one reaches the highest seventh plane of the cosmos, which here is called the region of the Creator, there is a necessity to come back.
Will continue soon