After the Frontispiece comes the Prologue:
(Gates of Paradise like everything else that Blake wrote is basically autobiographical (of his inner thoughts and feelings); It's also generic in the sense that it applies to the psyche of everyone (even you and me)).
We have here five couplets (without a picture):
"Mutual Forgiveness of each vice,Such are the Gates of Paradise"
Mutual Forgiveness is a threefold process:
We must forgive ourselves
We must forgive God
We must forgive one another, which is to say everyone.
To forgive yourself you must know yourself-- the hardest thing you will ever do. It may be something like the end of Mad Song:
"Like a fiend in a cloud
With howling woe,
After night I do croud,
And with night will go;
I turn my back to the east,
From whence comforts have increas'd;
For light doth seize my brain
With frantic pain."
It may mean 'frantic pain' to really know yourself, or are you truly who you think you are? In Jung's terms there's a world of difference between your selfhood and your self. But we may face that 'dark night of the soul' now or afterwards.
"Against the Accuser's chief desire,
Who walk'd among the stones of fire.
The Accuser of course is Satan, by Blake's side all his life (and yours? mine?) We've already written about the stones of fire.
"Jehovah's Finger wrote the Law;
Then wept; then rose in zeal and awe,
And the dead corpse, from Sinai's heat,
Buried beneath His Mercy-seat."
These two couplets might be seen as Blake's idea of the Old and New Testaments.
"O Christians! Christians! tell me why
You rear it on your altars high?"
Blake deplores the fact that Church too often was about sin and wrath rather than mutual forgiveness.