True knowledge, and not science falsely so called, is a 'divine thing,' as an excellent pen has proved it. For to know is to perceive truth, and the perception of truth is a participation of God Himself who is the truth, and the participation of God is the perfection of the mind.[Mary Astell, in The Christian Religion, section 262, as quoted in Jacqueline Broad, The Philosophy of Mary Astell, Oxford UP (New York: 2015), p. 40.]
Norris is the 'excellent pen' to whom Astell refers, and the passage in question appears in the second part of his Theory of the Ideal or Intelligible World (1704), where he says that since 'truth is of a divine extraction, and has a real divinity in its nature, what a divine thing must all true science be'. Astell's subsequent point likewise echoes Norris's observation that 'the Truth which we see is Divine, and...the knowledge which we have of Truth, is, in some degree a participation of the Divine Nature, and a kind of possession of God himself.'
Broad is referring to Part II of An Essay Toward a Theory of the Ideal or Intelligible World; she could also have noted the role played by truth as perfective of the mind in Part I (e.g., p. 334):
But besides, how comes Truth to be Perfective of our Minds? That it is so, may well be supposed our Understanding being then confessedly most perfect, when in the fullest Possession of Truth, when it has the clearest and largest View of it. But does not the whole Perfection of the Mind consist in its Union with God? Is not he our only perfective and beatifying Object, and can any thing else but his Divine Substance be the Good of our Souls?