Milton O Percival's William Blake's Circle of Destiny clarifies many of the mysteries in reading Blake. Percival includes chapters on The Seven Eyes, Sex Symbolism, Astrological Symbolism, and Alchemical Symbolism as well as less specialized subjects which characterize Blake's work. In this passage from his introduction he speaks of many familiar concepts of Blake's which contribute to the movement of fall and return which comprise the Circle of Destiny. Perhaps reading this will help you fit together some of the terms and ideas which form a thread through the maze of Blake's poetry.
Quoting from Percival:
"Even on the supernal level there is a rise and fall, a constant interchange of contraries, a wheel of departure and return. The exchange of Eden for Beulah involves descent; but so long as Beulah retains its faith in the values of Eden, the fall is not deep or severe, and the return is easy. But if in Beulah the error deepens and the circuit of return is closed, then the wheel has to swing "downwards and outwards," over a greatly expanded periphery, into the worlds of Ulro and Generation. For the punishment for error in Blake's system as in life itself lies in the bitter experience of error. When man decides, as he does in Beulah, without yet realizing the import of his decision, to live the outward, the passive, the feminine, the selfish, and the rational, he must be delivered over into the reality of his dream world in order that he may know it and renounce it. For experience, in Blake's system is remedial. Error runs its course. The spiritual body, like the natural body, labors to throw off infection and in the end succeeds. The path of experience is therefore circular. When the error which may be described as Nature or Natural Religion becomes formulated in man's mind, the cycle over which it is destined to run takes shape and begins to move. This cycle, which descends from Beulah into Ulro and ascends from Ulro by way of Generation into Beulah, where it joins the supernal cycle, is the Circle of Destiny."
Milton, Plate 30, (E130)
"Beulah is evermore Created around Eternity; appearing
To the Inhabitants of Eden, around them on all sides.
But Beulah to its Inhabitants appears within each district
As the beloved infant in his mothers bosom round incircled
With arms of love & pity & sweet compassion. But to
The Sons of Eden the moony habitations of Beulah,
Are from Great Eternity a mild & pleasant Rest.
And it is thus Created. Lo the Eternal Great Humanity
To whom be Glory & Dominion Evermore Amen
Walks among all his awful Family seen in every face
As the breath of the Almighty. such are the words of man to man
In the great Wars of Eternity, in fury of Poetic Inspiration,
To build the Universe stupendous: Mental forms Creating"