There are many realms within the Cosmos. There are realms that are more mundane than divine, and realms that are more divine than mundane.
the mundane realms
The most mundane realm is the most obvious - our everyday physical realm - the realm of the apparent "reality" of the world and the physical universe, where matter is very dense, and the cosmic illusions seem very "real".
Many people believe that this physical realm is all there is, and that all other realms are imaginary. But even the mundane realms contain depths that remain hidden to scientists. There are the astral realms - the domain of dreaming and imagination, where bodies are made of light, and forms can change at will. And there are mental realms of abstract and rational thought. These "imaginary" realms are just as "real" as the physical world, but those who think only rationally tend to dismiss these as figments of imagination - without stopping to consider what "imagination" is!
So, the mundane realms consist of the physical realm and many more subtle realms of dreams and imagination - the astral realms and mental realms. The entirety of the mundane realms are - like all of the cosmos - our mental creations. The physical realm is the most gross and "solid" of these mundane realms, but all are connected with the physical body and the ego-mind - so they are shaped not just by the divine mind but by the ego-mind also. And so they are influenced by the viciousness of the body and ego, as well as the divine influence that permeates all of the cosmos. And so the mundane realms are all expressions of our minds, and as such are subject to the same degradations and darkness as our ego-minds.
But divine alchemy is not much concerned with the astral and mental realms. Some people train themselves to operate consciously at will in those realities; but for self-transformation and ascension, the astral and mental realms are relevant to us only as training grounds and as indicators of our progress: we can tell that we are well on the way to complete self- transformation when our dreams become divine in nature. Otherwise, rather than focus on these realms, we instead learn to treat the physical realm as if it was an astral realm - we learn to interpret waking life as if it was a dream, as - from the perspective of the true self, the divine being - waking life is essentially no different to a dream, only in a more dense domain, where forms are more fixed and solid.
the divine realms
There are further subtle realms which are at a higher level of vibration than the astral and mental realms, and which are more divine than mundane in character. These divine realms are accessible only to divine consciousness. We can go there in deep meditation. Mundane consciousness cannot perceive these subtle realms, and is not compatible with these realms. Without divine consciousness these subtle realms remain hidden to us. These are the realms of "near-death-experiences", and the bardo state between incarnations. These realms can also be visited in divine trance.
The divine realms are infused with subtle divine light. These realms are visual - there is no sound at all, as sound only exists in the mundane realms, so these are "the silent realms". Within these divine realms, there are the soul realm, and red light, white light, and golden light realms.
the soul realm
The soul realm is the peak of divine experience. In the soul realm, we experience ourselves as divine beings and eternal souls, floating in absolute comfort and bliss in the eternal and unchanging realm of souls. Each of us is a conscious point of radiant golden love-light, within a translucent egg- shaped soul-body of orange light. You experience being the point of love-light - the divine being that is you - radiating the golden light of love and spiritual strength in all directions. You are within your translucent soul- egg, which contains all of your experiences - that is, the soul-egg contains all of your perception of the Cosmos. Any experience in any other realm is a creation of the divine being within the soul-egg.
In the soul realm we are aware of each other, as other radiant points of light each in their own soul-eggs identical in appearance to ours. We can sense each other's differing personalities and influence on each other, but we have to enter other realms to have more direct experience of each other.
realm of red light - the divine fire
The red light realm is the realm of divine fire, which we will examine later in more detail. In this realm the mundane body and ego-mind are cleansed by immersion in the divine love-light. All that is not divine in nature is consumed or repelled by the intense red light. Only that which is pure - that which is divine - can remain in the divine realms. The red colour is literally the "bonfire of the vanities" of the ego-mind, also known as "the flames of hell", though this implies a suffering that is not present in the divine fire. The divine fire purifies us.
realm of golden light - the divine heart
The golden light realm is the realm of the heart - the realm of pure divine consciousness, pure feeling, pure love. Here we experience our divinity - we are cocooned in divine love and divine bliss. We see only golden light, and we feel endless love and peace. This is the experience of simply being divine, unadulterated by any illusory forms of imagination.
realm of white light - the angelic realm
The white light realm is the realm of the divine mind - the realm of pure imagination, pure creativity, and the unlimited strength of divine will. Here is where all of the illusions of the mundane realms are created. This white light realm is the interface between the mundane realms and the divine realms: this is the light that we see and visit upon dying and in near-death experiences. This is the bardo where we go upon abandoning our physical bodies to death, and prior to taking another incarnation.
In the white light realm we still retain our human appearance from this incarnation, but in the form of very subtle ghost-like bodies of white light. These are our "angelic" bodies, our "perfect forms" - the divine blueprint for our physical bodies. They do not show details of our ageing or damage to our bodies - if you have lost a limb then your angelic body will still have that limb. This realm of angelic beings can also be described as "the angelic realm".
This white light angelic realm is itself infused with a white opacity, akin in appearance to mist with white light shining through it. When we are in this realm it is bit like being inside a cloud. There is the impression of being able to look down on the physical realm at will, but no sense of being pulled there by gravity.
Although there is no sound, we are able to communicate perfectly with each other by telepathy and by signals of the body - hands, arms, eyes. All scenes here are fluid and are conjured up and dispersed at will.
We can invoke anyone or anything into the angelic realm, and what will appear is the angelic form of that person or thing. We simply think - with a focused thought - of a particular person or being or object, and they will appear in front of us. The angelic form is, if you like, the subtle blueprint - actually white-print - of that being or object in its perfect form. It has the general shape of the physical form, albeit ghost-like, and the divine mind of that entity is also present.
From the angelic realm, we can also summon visions of any scene from the mundane realm, from any place and any time. We can, at will, dip in and out of the mundane realms and the associated mundane consciousness. We can experience not just the mundane present, but any scene from any of our incarnations, past or future. We can zoom in on - and out of - any Earthly scenes - past, present, or future. We can also experience the other divine realms from here - indeed any aspect of the cosmos. So, for the divine being, this white-light realm is "command central", if you like.
The absolutely pure consciousness of divine being is central to the cosmos, and inseparable from it: outwith the cosmos there is nothing but endless formless changelessness. The cosmos gives divine being form and experience.
Divine being manipulates and shapes the most subtle realms first of all, and then extends its influence through all of the increasingly gross and more complex realms. The entire cosmos is formed by the interplay between the fullness of divine being and the formless emptiness of divine matter. In elemental terms, divine being is spirit, and divine non-being - that is, all of creation - is shaped from various combinations of the fire of divine love-light and the water of divine matter. The interplay between these elements forms all of the cosmos.
The three subtle realms - of red light, golden light, and white light - form the interface between the mundane realms of human experience (fire and water), and the soul realm of divine being (spirit).
In divine alchemy we learn to transform our consciousness from mundane to divine, and to do so at will, so that we can move between the subtle divine realms and the more gross mundane realms at will. We come to regard the subtle realms as "home".