The purpose of death
The nature of life after death
How we can prepare for death
How we can assist the dying
What happens at death is so unspeakably glorious that our imagination and our feelings do not suffice to form even an approximation of it. C. G. Jung
The spiritual plane is the most real and eternal plane of creation. It's a realm of light beyond form, which includes many sub-planes and ascending levels. In some traditions it's called heaven, or the celestial realm. But these words don't do justice to the love, truth and beauty, which are the essential features of this plane. Presiding here are the great souls, as well as eternal forms, which serve as the template for the entire order of creation.
The spiritual plane marks the end of life after death and the beginning of eternal life, beyond the cycles of birth and death. During the first three stages after death, our experience is merely an echo of Earth life; a reflection of the psychic impressions from the life just lived. From this perspective, everything up to this point is the nature of a dream; an increasingly real dream, but a dream nonetheless. In contrast, the spiritual plane exists in its own right, beyond the Earth experience and the various astral planes.
Almost everyone has an intuitive awareness (conscious or subconscious) of the spiritual plane. It exists within us, individually and collectively, as our conscience, inner guidance and sense of highest good. It's this intuition that we reflect off when we're being courageous and true in the face of difficult circumstances. And it's during these times that we generate the greatest amount of spiritual essence.
The accumulation of spiritual essence is the purpose of human life and determines the evolution of our conscious experience. When our spiritual essence reaches a critical mass, it draws our awareness to the spiritual plane where it merges with the soul. Otherwise, awareness tends to get involved with another cycle of birth and death. But it's alright because our spiritual essence is never lost. It's continuously added to our evolving soul, which gains additional experience and depth with every cycle of Earth life.