Vibration is a kind of fine, subtle light. All scientists know that vibration is a kind of sound and light. If the sound is very fine, it turns into fine, subtle light that can be seen by our physical eyes. That's the basis of the working of television and radio stations: They send out microwave vibrations. All of the great spiritual practitioners emit such fine, subtle light, which is the so-called aura. The aura is a kind of fine, subtle light.
It’s said, "The light emitted from the Buddha’s hair transforms into billions of Buddhas." What does this mean? It means that one ray of this light can transform into many Buddhas. Why does it transform into so many Buddhas? "It transforms into countless Buddhas in order to deliver countless sentient beings." The light transforms into Buddhas who come down to the Saha world to deliver countless sentient beings. There are beings not just in this Saha world but in other worlds that are in a lot of trouble, and they need Buddhas to deliver them. That’s why the light "transforms into countless Buddhas in order to deliver countless sentient beings."
The souls of fellow initiates are not in their bodies anymore (but there is still communication between the two), because after initiation, the Master liberates the soul and sets it free by cutting the chain that binds the soul. Your body is still here and the soul is still connected to the body by a silver cord, but when your time is up and all of your fixed karma is paid off, the Master will cut the silver cord. At that time, you can walk away, leaving only the useless body behind, and then your soul will be forever free.
After initiation, if you don't continue with spiritual practice or listen to Master’s lectures or follow Master’s teachings, or if you practice other methods, then you need to come back to the Samsara world to learn again because you didn’t learn well and your soul is still in the lower level. This kind of soul must come down again to pay off the karma from his past wrongdoings.