From my own experience in study and both experience in soul travel and scrying, this is how I understand it. In the soul planes the highest dimension in what’s known as the formative plane, where the free flowing river of light and sound flows from. A eternal river of the formative essence that condenses as a fiery essence and forms all things.
From the source the ocean emanates, as it descends through the lower planes it changes, it adapts.
The further the essence travels from its origin I suppose you can say it undergoes a spiritual transmutation if you will. As the light descends from the formative plane, it enters into the highest dimension of the mental plane. Wherein the field of all consciousness exists, the light then passes through this field and absorbs a portion of that consciousness. The light tends to do this absorbing different things as it descends downward.
As it enters into the lower dimension of the mental plane, the once infinite field of consciousness takes on a individual spectrum of consciousness, a singular consciousness as opposed to the vastness of consciousness.
As it descends further down into the next plane, the casual plane it absorbs aspects of causality and memory, absorbing the memories of either past lives/reincarnation through Akashic infusion or just taking on the remnants of memory in general in the casual plane. Descending down now into the astral plane, this is where the soul becomes very unique as it randomly absorbs different energies in the astral plane.
This process is known as the transmigration process, as it descends downwards and changes over time. The light is now a soul manifest in the physical plane, which then descends into the flesh, i.e the soul enters the body/fetus/embryo etc.
Over time the individual realises they are indeed the source, separated from the source.