Swami Krishnananda, explains the Panchagni Vidhya from Chandogya Upanishad
Chandogya Upanishad, By Swami Krishnananda, Chapter 1, Discourse 2 & 3
(Extracts and paragraphs are realighned to suit ease of reading)
The Cosmic Interconnectedness
No event or no experience can be isolated from other experiences. The whole universal manifestation is a single process. It is continuity throughout from beginning to end, and births and deaths and other phenomenal experiences are not isolated factors. They are connected to ultimate causes.
This secret of Cosmic Interconnectedness and involution of factors are unknown to the senses and unthinkable to the mind. There is no such thing as a private act in this world. There is also no such thing as 'my' child and 'your' child. If this secret is known, no one will say, "It is my son, my daughter." It is neither yours nor anybody's. It belongs to that from where it has come. And from where has it come? It has come from every cell of the universe. It has not come from the seminal essence of the father or the mother, as it is believed. It is the quintessence of every particle of the whole of Nature, so that the cosmos is reflected in every body. That is why we say the brahmanda is in the pindanda - the macrocosm is in the microcosm. The cosmos is reverberating and is reflected in the little baby. How, then, can you say that it is your child? It is the child of the universe, which is to take care of it; and it shall withdraw it when it is to be summoned back; it projects it when it is to be sent out for reasons which are known to the universal law alone.
The Vidhya takes the standpoint of the wider background that operates behind every event in the phenomena of natural processes. Things are not what they seem; there is a deeper significance behind every visible process or activity in Nature. This is the esoteric side, or the invisible aspect of the visible phase of our practical existence. It is not that events suddenly emerge out into visibility, as if by magic, and that something happens at one stroke.
The cause of a particular event which is ordinarily regarded as normal, physical, personal, social, visible, tangible, etc., this particular thing, has a transcendent secret behind it. There is a total activity, in a subtle form, taking place prior to the apparently individual expression of it in the form of experience and perception.
The Upanishad tells us, here, that the first vibration propelling any kind of activity or event in this world takes place not in this world alone, but in a higher realm. The cause has to be churned first in order that the effect may feel the impact of that stir in the cause. Now, the cause is not merely a single factor. There is a chain of factors involved in the conception of the cause. If, for the purpose of our study, we may say A is the effect that is physically felt by us in this world, it has a cause which is B, impelling this effect to manifest itself in that particular manner in the physical world. But, this B which is the cause of A has another cause behind it, which is C. So, we may say, that B is the cause of A, or we may say, C is the cause of A because it is the cause of B also. But, this C has another cause behind it, and that is D. So, while D is the cause of C and B, and through these, of A, we may also say that it is the cause of the last effect also. Thus, the first cause is the real cause which pushes itself downwards to lower levels of reality, until they express themselves in space and time. This expressed form in space and time alone is known by us, seen by us, felt by us and experienced by us.
A mystery in this connection is mentioned here. What is our connection with these higher regions of the world? The higher regions are, in fact, not unconnected with us. The shining of the sun or the moon, the twinkling of the stars, or the blowing of the wind - all these phenomena are vitally connected with our own life here. They are not just something taking place somewhere erratically, as if they have nothing to do with anyone. Our life is related to every phenomenon outside, and vice versa. While our way of living has something to do with the activity of the world outside, our life is also dependent on that activity. There is a mutual dependence between the outer world and the inner life of the individual. Our thoughts influence the atmosphere.