ROBERT BLAKE

The family member to whom William Blake was most attached was his brother Robert who was five years younger than he. Robert shared William's interest in art. A Robert Blake was accepted into the Royal Academy in 1782 but his date of birth does not match the probable birth date of William's brother. What is known about  William's brother is that he made drawings which influenced William. We know also, from the 1863 Gilchrist biography, that when Robert lay dying at the age of 19, William nursed him constantly for two weeks without rest and then watched as his brother's spirit ascended heavenward.
 
One of Blake's first experiments in relief etching reflects a drawing attributed to Robert by Gilchrist on the authority of Tatham, who acquired the residue of Blake's work on the death of Catherine Blake.

British Museum
Sketch by Robert Blake Approach of Doom

British Museum
Engraving by William Blake Approach of Doom

The experience of the death of his beloved brother confirmed Blake's belief in immortality. The spiritual presence of his brother remained real to Blake throughout his life. The notebook in which Robert had made sketches was treasured by William after his brother's death. William sketched and wrote notes and drafts of his poems in the hand-me-down notebook from his brother until every available space was filled with the inspirations which came to him.

Letters, (E 705)
[To] William Hayley Esqr, Eartham,
near Chichester, Sussex
Lambeth May 6 1800.  
Dear Sir
     I am very sorry for your immense loss, which is a repetition
of what all feel  in this valley of misery & happiness mixed--I
send the Shadow of the departed Angel.  hope the likeness is
improved.  The lip I have again lessened as  you advised & done a
good many other softenings to the whole--I know that  our
deceased friends are more really with us than when they were
apparent  to our mortal part.  Thirteen years ago.  I lost a
brother & with his spirit I  converse daily & hourly in the
Spirit.  & See him in my remembrance in the  regions of my
Imagination.  I hear his advice & even now write from his
Dictate--Forgive me for expressing to you my Enthusiasm which I
wish all to  partake of Since it is to me a Source of Immortal
Joy even in this world by it  I am the companion of Angels.  May
you continue to be so more & more & to  be more & more perswaded. 
that every Mortal loss is an Immortal Gain.  The  Ruins of Time
builds Mansions in Eternity.--I have also sent A Proof of 
Pericles for your Remarks thanking you for the kindness with
which you  Express them & feeling heartily your Grief with a
brothers Sympathy 
I remain Dear Sir Your humble Servant
WILLIAM BLAKE

Perhaps more unusual than the spiritual consolation Blake felt from Robert's constant presence, was the practical assistance which William acknowledged that he received from his brother as he worked out the technique for producing his illuminated engraved books.

This passage about William's struggle to invent a way to publish his graphic work with accompanying text is from page 70 of The Life of William Blake by Alexander Gilchrist:

"He had not the wherewithal to publish on his 
own account; and though he could be his own engraver, 
he could scarcely be his own compositor. Long and deeply 
he meditated. How solve this difficulty with his own in- 
dustrious hands? How be his own printer and publisher? 
The subject of anxious daily thought passed — as anxious 
meditation does with us all — into the domain of dreams 
and (in his case) of visions. In one of these a happy In- 
spiration befell, not, of course, without supernatural agency. 
After intently thinking by day and dreaming by night 
during long weeks and months, of his cherished objective the 
image of the vanished pupil and brother at last blended 
with it. In a vision of the night, the form of Robert 
stood before him, and revealed the wished-for secret 
directing him to the technical mode by which could be 
produced a fac-simile of song and design. On his rising 
in the morning, Mrs. Blake went out with half-a-crown, 
all the money they had in the world, and of that laid
Is. 10d. on the simple materials necessary for setting in 
practice the new revelation. Upon that investment at 
Is. 10d. he started what was to prove a principal means of 
support through his future life, — the series of poems and 
writings illustrated by coloured plates, often highly finished
afterwards by hand, — which became the most efficient and 
durable means of revealing Blake's genius to the world. 
This method, to which Blake henceforth consistently 
adhered for multiplying his works, was quite an original
one. It consisted in a species of engraving in relief both 
words and designs. The verse was written and the designs 
and marginal embellishments outlined on the copper with 
an impervious liquid, probably the ordinary stopping-out 
varnish of engravers. Then all the white parts or lights, 
the remainder of the plate that is, were eaten away with 
aquafortis or other acid, so that the outline of letter and 
design was left prominent, as in stereotype. From these 
plates he printed off in any tint, yellow, brown, blue, 
required to be the prevailing, or ground colour in his fac- 
similes ; red he used for the letter-press. The page was 
then coloured up by hand in imitation of the original 
drawing, with more or less variety of detail in the local 
hues." 

It is believed that Blake may have included the instructions for creating his illuminated books in Island in the Moon but removed them to maintain secrecy. He left this fanciful passage about how lucrative the process might prove to be.

An Island in the Moon, (E 465)
PAGE X
"them Illuminating the Manuscript--Ay said she that would be
excellent.  Then said he I would have all the writing Engraved
instead of Printed & at every other leaf a high finishd print all
in three Volumes folio, & sell them a hundred pounds a piece.
they would Print off two thousand   then said she whoever will
not have them will be ignorant fools & will not deserve to live"