Eden is a common name for The Garden where the first man and woman lived in innocent bliss; but they preferred consciousness (in terms of the knowledge of Good and Evil) and were cast out of Eden. Look at Genesis 3.
Re 3:24 (3:24 So he drove out the man; and he placed at the east of the garden of Eden Cherubims, and a flaming sword which turned every way, to keep the way of the tree of life) , this comment is useful:
"The flaming sword keeps the way of the tree of life. William Blake had an idea going beyond what the writer of Genesis could say:
"For the cherub with his flaming sword is hereby commanded to leave his guard at the tree of life, and when he does, the whole creation will be consumed, and appear infinite and holy whereas it now appears finite & corrupt." (Marriage of Heaven and Hell, Plate 14)
We might also cite some passages in Revelation (near the end) where the 'tree of life' reappears. Both Blake and the writer of Revelation were speaking of the Parousia."`Ezekiel's Covering Cherub (Ezekiel 28:1-19) might well be seen as the contrary of Heaven. Blake identified it with the angel with the flaming sword at the Gate to Paradise. Somewhere in Fearful Symmetry Northrup Frye described the human desire for fulfilment like this: you have only to jump through the ring of fire. (Frye mentioned the Cherub often in his classic.)
A reader of "Final Lesson" made this comment:
" is Heavens gate meant to lead IN to Jerusalem through the wall, or OUT of Jerusalem through the wall?
When I think of the actual gates in the walls around Jerusalem, they go both ways... in and out of the city...
But "heavens gate" sounds like a gate into heaven.
Do you see my confusion...? "
First of all "heavens gate" is a gate into heaven!
Most of us hope to go in; Jesus and John Milton came out!
So what is "Jerusalem's wall"? Well what is Jerusalem? A symbol (it means many
things to many people!) Jerusalem, the emanation of Albion may symbolize 'that of God in you'; Jerusalem is the bride of Christ. Jerusalem is Imagination. Jerusalem of course is a city in Palestine. The New Jerusalem IMO is subtantially equivalent to Heaven.
Blake's two versions of The Gates of Paradise are well worth looking at. In this context we may see the Gates represent steps along our mortal journey into Eternity or immortality.
Blake's system and myth included four walls and four gates, one in each direction. For example the Western Gate (Tharmas) is sense based, material, and hence only mortal.
Note: Computers vary widely with their output; people's acuity of sight also varies widely. to read comfortable older people need bigger type; when a post is projected on the wall, a large type face is desirable.