Who is H's Reappearing Intellect from A Grief Observed and what is their importance?

Toward the end of the book, Lewis describes an encounter with what he describes as the stripped-down intellect of his wife. He sat amazed and reveling in the cleanliness of an encounter of love without the cloudiness of emotion. The only emotion he does describe is joy, pure and crisp, as if removed from the encumbrance of the human nervous system and incomplete mind. The encounter leads Lewis to wonder whether that is the kind of perfect relationship humanity will experience in heaven, without the clumsy and limited humanity through which relationships are translated on earth.