“The next point to be considered is how these bodies behave in the process of successive reincarnations as this will grant us a better understanding of the principal aspect of Diversity in the human brotherhood, which is the fact that humanity is made up of beings of different ages or different stages of spiritual evolution. This is so because this process of reincarnations explains the different accumulation of experiences, which lies at the basis of the different levels of maturity or spiritual development of human beings.
In a first stage, the divine energies create and surround themselves with ever denser levels of matter until reaching the physical plane. From this point on, as has been mentioned previously, these energies animate the mineral, vegetable, animal, human, and super-human kingdoms until they return fully conscious to the bosom of the One Divinity. Human beings, therefore, have immediately behind them the animal kingdom from which they rose as beings who have acquired their own individuality through the act of liberating themselves from the limitations of group consciousness typical of animal instincts.
It is only at this point in evolution, at the beginning of the human stage, that man’s Higher Ego has become an individual spiritual entity, thus acquiring freedom of thought and a much higher consciousness of self than it had in the animal kingdom. This Higher Ego, however, has not yet developed its immense latent powers. It will gradually develop these powers as the human being passes through successive reincarnations.
At the beginning of each incarnation, the Higher Ego creates a new lower quaternary to enable it to gather more experiences on the Physical, Astral, and Lower Mental planes. The physical life is usually the shortest, although the most meaningful one as it is the only one during which the human being encounters all the bodies and, therefore, has greater independence and power to generate new causes and search for new experiences.
After having existed for years in the physical body, man arrives at the passage called death when he abandons the dense physical body and the etheric double, which are both worn out and no longer of service to garner more experiences, and departs for a life on the astral plane with the help of his astral body. This life normally lasts two or three times longer than physical life, and then this astral body is left behind in a second death, which is another passage to a life normally even longer on the lower mental plane. At the end of this cycle, the Higher Ego garners the results or lessons of the experiences lived through its lower quaternary on the three densest planes.
This is a simple description of the process through which the Higher Ego develops its infinite powers until it reaches a stage of maturity and perfection in which this cycle of reincarnations is no longer mandatory. In other words, at the end of this long journey through hundreds of reincarnations, the human being achieves Liberation, and his consciousness enters a super-human stage of development, one of whose characteristics is the fact of having achieved conscious immortality and the other is the unity with the Divine Will. One of the names given to this Liberation is that of “Adeptship.” The Adepts or Mahatmas who inspired the founding of the TS are believed to be examples of beings who have already achieved this evolutionary level.
All human beings are engaged in this process of development of their divine powers because, as has been stated previously, all are essentially divine. However, the billions of incarnate human beings, as well as those (in even larger numbers) without a physical body in the cyclical astral or mental life, will not start out on their human journey at the same time. Some of them have begun their journey long before others. Thus, while some have already arrived at their destination and others are nearing the end of their journey, the greater part of humanity can be found along this way, some of them even at its beginning. This is a very important fact as it explains the great diversity in stages of spiritual development (reflected in the differences of character and ability) in human beings.
In view of the above, it is not difficult for us to understand that this aspect of the great Diversity in the levels of spiritual development is almost as important in helping us understand the true nature of the universal brotherhood of humanity, as that of the Unity underlying all beings.” (Arnaldo Sisson Filho. Theosophy and Universal Brotherhood, — Chapter VII)