The Son of man is the awakened self rising within the crown of the head, the higher mind returning to rule where the lower mind long sat. Heaven is not overhead but the upper chamber of consciousness, and the clouds are the dimming thoughts that gather just before that inner light breaks through them. When it comes, the scattered tribes of the earth grieve because the earth is the body and its tribes are the many divided desires that ruled a person; each one mourns the loss of its old dominion.
The great glory is the flood of clear awareness filling the mind. What arrives is your own true self taking its throne, and every lesser part of you feels the ground shift as it does.
Son of man: the awakened higher self forming within, the true ruler returning to the mind
Heaven: the upper chamber of consciousness inside the skull, not a place above the world
Clouds: the darkened, crowding thoughts that mass just before inner light breaks through
Tribes of the earth: the many divided desires and appetites of the body, each losing its rule