As Blackstone introduces his book, he makes a comment on the Norman Conquest:
That antient collection of unwritten maxims and customs, which is called the common law, however compounded or from whatever fountains derived, had subsisted immemorially in this kingdom; and though somewhat altered and impaired by the violence of the times, had in great measure weathered the rude shock of the Norman conquest. This had endeared it to the people in general, as well because it's decisions were universally known, as because it was found to be excellently adapted to the genius of the English nation.What is going on here is important: because it forms the basis of a link that Blackstone will later make between English religion and English law. The crux of this paragraph is an opposition that Blackstone creates between two theories of origin for the English law. The first theory suggests that English law was the act of a leglislator at a particular point in time. The clearest such point in time was the Norman Conquest- hence Blackstone's mention of 1066 and he like every common lawyer- including Sir Edward Coke, John Selden and Sir Matthew Hale- of the previous century denied that the Norman Conquest represented an overthrow of English law. Rather Blackstone argues that there was a mysterious moment- somewhere in the immemorial past- where a set of judgements and laws came together into the common law. Essentially this is a story about the origin and meaning of law- either law is a rationally formed thing, created in a moment by a leglislator (think of Lycurgus or Solon)- or it is brought together, compounded out of fountains of thought in the deep past.
Notice Blackstone says that the Norman Conquest changed the law. He could hardly not have said that given the work done by Henry Spellman and others in the late seventeenth century which demonstrated conclusively that the law of England had been fundementally changed by the Conqueror. But what he wants to do is to deny that was a moment in which the law was created. Indeed Blackstone derives the law's utility- its legitimacy- from the fact that he believes it is both uniquely understood by the English and uniquely suited to their needs. It is constructed by usage. We will come to see in the next post why that's a crucial idea for Blackstone as a defender of the Church of England. It is also a crucial link between early modern ideas about law and conservative ideas in the English tradition. What Blackstone is arguing for is a system of legal knowledge which is established over centuries, binding together generations and which has become a language in which politics can be most appropriately described. This is the Whig conception of the constitution- and one only has to think of Burke's thinking, as Pocock has argued, to see how influential this idea of an organic language which constructs the state and its relationship to its citizens has been.