How does Krsna grow if He doesn't change His body?

In the course of His pastimes, Krsna grows and his body apparently changes. He starts as a small child and becomes a handsome youth by the time he fights Kaṁsa. How can we understand that?

In the Bhagavad-Gita (2.16), Krsna explains that everything that is spiritual doesn't change. That's one of the differences between material and spiritual. Everything that is material changes, and these changes eventually lead to its death or destruction. Everything that is spiritual, on the other hand, doesn't change and is therefore eternal.

However, one may notice an apparent contradiction: in the course of His pastimes, Krsna grows, and his body apparently changes. He starts as a small child in the hands of Vasudeva and becomes a handsome youth by the time he fights Kaṁsa. How can we understand it?

The point is that Krsna's body doesn't change. Krsna has infinite forms and pastimes, and in the spiritual world, all these pastimes happen eternally and simultaneously. In the material world, time is perceived as a sequence of events that we can fit into a timeline, but in the spiritual world, time is different in nature, and all pastimes happen simultaneously for eternity, something that is very difficult for us to understand.

When Krsna comes to this material world, He has to show His pastimes in a format that we can understand. Therefore, He shows His pastimes sequentially, creating a timeline of events, appearing first as a small child, then as a boy, a grown-up man, and so on. However, there is no change in His body; He just shows his different forms and pastimes in a certain order, in a format that is suitable to our understanding.

This is obviously different from our situation since we assume material bodies. Although the soul never changes, the material body passes through many different transformations and ultimately dies. Pure devotees don't have material bodies in the sense that their bodies are spiritualized due to their service and devotion to Krsna, just like prasāda is spiritualized. Still, technically speaking, they assume material bodies that change and eventually have to be left behind.

Srila Prabhupada explains that although Krsna and Arjuna are eternal friends and they go together from one universe to another, Krsna never forgets anything because he always comes in His eternal spiritual body. Arjuna, however, is an infinitesimal soul and accepts a new body every time. Because of this, he can forget what happened in the past. Krsna could perfectly remember that He spoke the Bhagavad-Gita to Vivasvān millions of years ago, but Arjuna could not. This illustrates the difference between Krsna and the jīva. Even a perfect soul like Arjuna has to accept a material body when he comes to this material world (although such a body is spiritualized due to his service to Krsna), Krsna, however, never accepts a material body.

Mayavadis can't understand this distinction and, as a result, they believe that when Krsna comes to the material world, He accepts a material body and comes under the influence of Maya, performing activities under the material mode of goodness. They at least have the decency of refraining from accusing Krsna of falling into passion and ignorance, but in any case, the practical consequence of their conclusion is the same: that Krsna falls into Maya like us, assumes a material body, and performs material activities.

This is why their philosophy is called Maya-Vada. Vada means a doctrine, and Maya indicates this incorrect belief that Krsna assumes a material body.

Just like Krsna's body is spiritual, eternal, and unchangeable, the same applies to the transcendental forms of all incarnations, like Nrsimha, Varaha, Vamana, and so on. They are all eternal. The idea is that the Lord does not create the fish incarnation, for example. He eternally has such a form, and the appearance and disappearance of His different incarnations serve particular purposes. Krsna has thus not only unlimited pastimes, but also unlimited forms, and all these forms and pastimes exist eternally in the spiritual world. When Krsna desires to appear in this material world, He comes in His original spiritual body and shows one or a few pastimes at a time in a format we can understand, just like an actor can assume different roles in different plays without changing his body.