'clearing away the rubbish' The first chamber is the dark cavern of the unconscious. It is a typical starting point in any movement of psychological development. The Cosmic egg must be cracked, the cultural rut must be breached, the bottom must be reached or the need for change must be acknowledged. This prepares the surface of the copper (or the hardened rituals and routines) to receive the images which will modify and transform it.
'folding round the rock & the cave, and others adorning it' The second chamber in which the design is executed allows the rational mind to have its say. A plan is made and transferred to the surface. The plate is not the image itself but the means by which the image may come forth. The plate is incised, reversed, manipulated. It is a material object or state but it is only a transient stage in the evolutionary process.
'caused the inside of the cave to be infinite' The Eagle of Imagination occupies the third chamber where the acid bath removes copper which has not been protected by waxed applications. This is the stage which is not controlled by the artist but by the action of the acid which acts as the agent of the imagination. The furnaces of Los are forever engaged in this process of removing what can and must be discarded.
'melting the metals into living fluids' In the fourth chamber the inks are prepared using fire and fluids. They are applied to the surfaces which stand elevated as mountains above the valleys of etched copper. 'cast the metals into the expanse' All that went before this step was preparation, The sixth chamber sees the inked plates meet the expanse of paper which are ready to receive them and prove that the process has brought forth the product of imagination first conceived.
'took the forms of books' In the sixth chamber the artists prepare to release their 'children' to go into the world. What had been internal has become external, what had been eternal has become temporal, what had been a seed has come to fruition. The cocoon has released the butterfly.
'This is all for the purpose of transmitting knowledge from generation to generation.' In this our world of generation this is the method through which Blake can transmit his knowledge to the generations which come after. But unless the printed pages open the minds of men to the 'perception of the infinite', we remain in the first chamber amidst our clutter.
Milton, Plate 28 (30), (E 126)
"But others of the Sons of Los build Moments & Minutes & Hours And Days & Months & Years & Ages & Periods; wondrous buildings And every Moment has a Couch of gold for soft repose, (A Moment equals a pulsation of the artery) , And between every two Moments stands a Daughter of Beulah To feed the Sleepers on their Couches with maternal care. And every Minute has an azure Tent with silken Veils. And every Hour has a bright golden Gate carved with skill. And every Day & Night, has Walls of brass & Gates of adamant, Shining like precious stones & ornamented with appropriate signs: And every Month, a silver paved Terrace builded high: And every Year, invulnerable Barriers with high Towers. And every Age is Moated deep with Bridges of silver & gold. And every Seven Ages is Incircled with a Flaming Fire. Now Seven Ages is amounting to Two Hundred Years Each has its Guard. each Moment Minute Hour Day Month & Year. All are the work of Fairy hands of the Four Elements The Guard are Angels of Providence on duty evermore Every Time less than a pulsation of the artery Is equal in its period & value to Six Thousand Years. PLATE 29  For in this Period the Poets Work is Done: and all the Great Events of Time start forth & are concievd in such a Period Within a Moment: a Pulsation of the Artery."