Metatron, also known as Lord Regent, is the enforcer of the Authority's will and vehemently attack all those who question it. He is portrayed by Pullman as a tyrannical leader of blind faith. Pullman keeps to some factual aspects, such as the fact that he was initially the human Enoch. Metatron is literally said to be the voice of God and led the people of Israel through Egypt.
Interestingly, Metatron is linked through geometry to the Tree of Life and the theme of the fall of man. Metatron's Cube is a geometric shape that is considered a holy glyph and the symbol of Metatron himself. It is formed from the symbol of the Fruit of Life pattern, you can see this process in the video below.
This article describes the dangerous nature of this story for religious scholars and describes Ezekiel - chapter 1, where the Chariot appears. This Wikipedia entry also goes in to some detail on Merkabah, otherwise known as The Chariot, describing a very different form from Pullman's; it is formed from four angels each with four heads and so on.
Pullman, however, does put to rest any debate on who is sat upon the Throne on the Chariot. For religious scholars it was impossible for it to be God as God cannot speak to humans, though it spoke with his authority. Pullman answers these with the Lord's Regent, Metatron, who speaks on God's behalf.
The Chariot is also referred to as the 'chariot of fire' in Blake's poem 'Jerusalem', which provides an epigraph later in the novel.
Chapter 3 Epigraph
Author: S. T. Coleridge
Work: The Knight's Tomb
Here's the poem in full with some commentary.
Pullman is pulling together metaphysical notions of free will, theological debates surrounding God, questions of physics in the form of Dust (or matter) and here he draws in yet another debate, the ecological one. While climate change is a clear and present danger in our world, so too is it for Lyra's. Like the harmful CO2 gasses that we are not able to see, should we disassociate it with its religious connotations, Dust too has many similarities. Indeed, the threat takes on an even more deadly form in the world of Cittàgazze, where they are the cause of Spectres that feed on the soul.
In fact, New Line Cinema teamed up with the World Wildlife Fund to produce an advert to educate . They concentrate on this exact problem with polar bears and their shrinking habitat. Here's the advert...
Chapter 4 Epigraph
Author: Emily Dickinson
Work: She lay as if at play
You can check out this with other of her works on Google Books.