In these three passages from Paradise Lost, two of the most central ideas are those of ineffability and redemption.
Ineffability is an ironic subject for a poem, since it refers to something too sacred to be described in words. Milton is continually aware of this tension as a Christian and a Puritan. He is describing something which many of his co-religionists believe should not be described as a matter of principle. In trying to depict the glory of God, however, he is also setting himself up for artistic failure. Milton describes the ineffability of God as a blaze of light, similar to the sun in that one cannot look directly at it. It is the Son (a weak but unavoidable pun) who makes the brightness of God visible, since it is in his "conspicuous countenance" that "th'Almighty Father shines."
The Son is a mediator between God and Man. His divine nature is ineffable, but his human form, though glorious in its way, like the forms of Adam and Eve, is of a different type. It is this dual nature that allows him to perform his role as the redeemer of humankind. In the two extracts from book 6 of Paradise Lost, where God addresses the Son directly, he makes it clear that the Son participates in his own ineffable nature but is also human and visible, which makes him able to bring redemption to humanity. This role, which the Son is to fulfill in Paradise Regained, is continually foreshadowed throughout Paradise Lost and has led some critics to regard the Son as an epic hero of both poems.