"I consider them [Bacon, Newton, and Locke] as the three greatest men that have ever lived, without any exception.." (from the pen of Thomas Jefferson in a letter in 1789.
You can see what Blake thought of Bacon by reading his annotations to one of Bacon's books (Erdman pp 620-32). Here's are two examples:
"7. Bacon a Liar
8. Bacon has no notion of any thing but Mammon
Re Newton look at the end of a famous letter (23) to Butts in 1802:
"Now I a fourfold vision see And a fourfold vision is given to me Tis fourfold in my supreme delight And three fold in soft Beulahs night And twofold Always. May God us keep From Single vision & Newtons sleep" (Erdman 722)
Re Locke: the tabula raza was particularly offense to Blake who thought intelligence and imagination were inherent in us all.
In Milton plate 41 Blake dispatches all three with this: "To cleanse the Face of my Spirit by Self-examination. To bathe in the Waters of Life; to wash off the Not Human I come in Self-annihilation & the grandeur of Inspiration To cast off Rational Demonstration by Faith in the Saviour To cast off the rotten rags of Memory by Inspiration To cast off Bacon, Locke & Newton from Albions covering To take off his filthy garments, & clothe him with Imagination" (Erdman 142) Blake felt that these three men (Blake's 'unholy trinity') had led England into a thoroughly materialistic, spirit-denying culture dominated by greed. What he said about them was largely true although they had a positive dimension as well. Blake acknowledged the positive dimension
in plate 98 near the end of Jerusalem:
"The Druid Spectre was Annihilate loud thundring rejoicing terrific vanishing Fourfold Annihilation & at the clangor of the Arrows of Intellect The innumerable Chariots of the Almighty appeard in Heaven And Bacon & Newton & Locke, & Milton & Shakspear & Chaucer"(Erdman 257)
Although he had excoriated them systematically throughout his works, he realized that they were not negatives, but contraries. The essential polarity of the mind means that the opposites are also true.