A Citation:
Since every living entity is an individual soul, each is changing his body every moment, manifesting sometimes as a child, sometimes as a youth, and sometimes as an old man. Yet the same spirit soul is there and does not undergo any change. This individual soul finally changes the body at death and transmigrates to another body; and since it is sure to have another body in the next birth—either material or spiritual—there was no cause for lamentation.
Rather, he should rejoice for their changing bodies from old to new ones, thereby rejuvenating their energy. Such changes of body account for varieties of enjoyment or suffering, according to one's work in life.
Any man who has perfect knowledge of the constitution of the individual soul, the Supersoul, and nature—both material and spiritual—is called a dhira or a most sober man. Such a man is never deluded by the change of bodies.
The Shankarcarya theory of oneness of the spirit soul cannot be entertained on the ground that spirit soul cannot be cut into pieces as a fragmental portion. Such cutting into different individual souls would make the Supreme cleavable or changeable, against the principle of the Supreme Soul being unchangeable.
As confirmed in the Gita, the fragmental portions of the Supreme exist eternally (sanatana) and are called ksara; that is, they have a tendency to fall down into material nature. These fragmental portions are eternally so, and even after liberation, the individual soul remains the same—fragmental.
The theory of reflection can be applied to the Supersoul who is present in each and every individual body and is known as the Paramatma, who is different from the individual living entity.
When the sky is reflected in water, the reflections represent both the sun and the moon and the stars also. The stars can be compared to the living entities and the sun or the moon to the Supreme Lord.
The individual fragmental spirit soul is represented by each individual soul, and the Supreme Soul is the Personality of Godhead.
They are not on the same level, the Supreme Lord is superior in position to the living soul, who is deluded by maya.