In Book 5 of Paradise Lost, Adam asks the angel Raphael a lot of questions, and he mentions several times the difficulty of describing and explaining heavenly matters in mortal language. Raphael's awareness of this problem registers Milton's own awareness of the same difficulty, a difficulty exacerbated by the Fall, which makes language an imperfect vehicle of communication (it was presumably perfect before the Fall).
Questions About Language and Communication
What effects does the Fall have on Adam and Eve's ability to communicate?
What effects does the Fall have on language in general?
Do Adam and Eve have any communication problems before the Fall?
Chew on This
Milton's attempts to describe Paradise always fall short because the fallen medium he uses brings a lot of semantic baggage with it.
In Eden, language is the perfect communicative tool; as we learn when Adam names the animals (Book 8), language somehow incorporates some aspect of the nature of what it names.