The classical theories of science are based upon the universe as a closed system. The sum-total of matter/energy is finite and unalterable. Newton Laws are based on this premise. Blake may have had many objections to Newton's science and his religion but the idea of a material universe which allowed no input from the non-material eternal world would have been especially repugnant to him. Believing as he did that for every natural event there is a spiritual cause, Blake acknowledged continual intervention in the human world by the Divine. Urizen's compulsion to create a solid, enclosed order for which the future was predetermined was Blake's representation of the consequences of excluding the energy of imagination from the psyche.
The development of systems thinking as a replacement to the Cartesian paradigm is outlined in The Web of Life: A Scientific Understanding of Living Systems by Fritjof Capra. Parallels to Blake's thought are apparent in many particulars. Blake would have been more comfortable with systems thinking than with the system of analyzing and reducing every whole into independent parts.
Quotes form The Web of Life:
"According to the systems view, the essentials of an organism, or living system, are properties of the whole, which none of the parts have. They arise from the interactions and relationships of the parts. These properties are destroyed when the system is dissected, either physically or theoretically, into isolated elements."
"The old paradigm is based on the Cartesian belief in the certainty of scientific knowledge. In the new paradigm it is recognized that all scientific concepts and theories are limited and approximate. Science can never provide any complete and definitive understanding."
Milton, Plate 26 , (E 124 "In Bowlahoola; & as the Spectres choose their affinities So they are born on Earth, & every Class is determinate But not by Natural but by Spiritual power alone, Because The Natural power continually seeks & tends to Destruction Ending in Death: which would of itself be Eternal Death And all are Class'd by Spiritual, & not by Natural power. And every Natural Effect has a Spiritual Cause, and Not A Natural: for a Natural Cause only seems, it is a Delusion Of Ulro: & a ratio of the perishing Vegetable Memory."
Jerusalem, Plate 42, (E 189) [Los to Albion] "I have no time for seeming; and little arts of compliment, In morality and virtue: in self-glorying and pride. There is a limit of Opakeness, and a limit of Contraction; In every Individual Man, and the limit of Opakeness, Is named Satan: and the limit of Contraction is named Adam. But when Man sleeps in Beulah, the Saviour in mercy takes Contractions Limit, and of the Limit he forms Woman: That Himself may in process of time be born Man to redeem But there is no Limit of Expansion! there is no Limit of Translucence. In the bosom of Man for ever from eternity to eternity. Therefore I break thy bonds of righteousness; I crush thy messengers! That they may not crush me and mine: do thou be righteous, And I will return it; otherwise I defy thy worst revenge: Consider me as thine enemy: on me turn all thy fury But destroy not these little ones, nor mock the Lords anointed: Destroy not by Moral Virtue, the little ones whom he hath chosen! The little ones whom he hath chosen in preference to thee. He hath cast thee off for ever; the little ones he hath anointed! Thy Selfhood is for ever accursed from the Divine presence So Los spoke: then turn'd his face & wept for Albion."
Jerusalem, Plate 30 , (E 177) "If Perceptive Organs vary: Objects of Perception seem to vary: If the Perceptive Organs close: their Objects seem to close also: Consider this O mortal Man! O worm of sixty winters said Los Consider Sexual Organization & hide thee in the dust. PLATE 31  Then the Divine hand found the Two Limits, Satan and Adam, In Albions bosom: for in every Human bosom those Limits stand. And the Divine voice came from the Furnaces, as multitudes without Number! the voices of the innumerable multitudes of Eternity. And the appearance of a Man was seen in the Furnaces; Saving those who have sinned from the punishment of the Law, (In pity of the punisher whose state is eternal death,) And keeping them from Sin by the mild counsels of his love."