What can be inferred about Heathcliff's experience on the moors after he has been out all night?Emily Bronte's Wuthering Heights

In Chapter 33 of Wuthering Heights,
after a violent conflict with young Catherine and Hareton, Heathcliff confides in Nelly
that a strange change approaches as the two young people cause him much
agony:

...I
earnestly wish she were invisible:  her presence invokes only maddening sensation. He
moves me differently:  and yet if I could do it without seeming insane, I'd never see
him again! 

Heathcliff
cautions Nellie to respect his confidence in her as he speaks of how Hareton's
resemblance to Catherine haunts him.

readability="10">

"In every cloud, in every tree--filling the air
at night, and caught by glimpses in every object by day I am surrounded by her
image!....The entire world is a dreadful collection of memoranda that she did exist, and
that I have lost her!"

As the
chapter ends, Heathcliff speaks of a change that worries Nelly.  Then, in Chapter 34, he
returns from having been out all night; there is an unnatural "appearance of joy under
his brows," and Heathcliff's teeth chatter, not with cold, but with a "strange
thrilling."  He tells Nelly that the night before he was on "the threshold of hell," but
this day he has sight of heaven.  When Nelly sets food before Heathcliff, he starts to
eat, but his hands clench and he has a ghostly paleness about his features.  Fearful of
him, Nelly leaves the room.

When she returns, Heathcliff,
who appears excited, asks Nelly if they are alone.  She affirms that they are, yet
Heathcliff appears to gaze at something with a "raptured" expression.  That evening
Nelly hears him call the name of Catherine, and the following morning he explains to
Nelly that he is unable to eat because his bliss kills his
body:

"I have
nearly attained my heaven; and that of others is altogether unvalued and uncoveted by
me!"

Heathcliff's wild looks
and distracted behavior and strange happiness after spending the night on the moors
suggests that he has encountered the ghost of Catherine Earnshaw.  When he dies with the
"life-like gaze of exultation" upon his face and the latticed window is open, it would
appear that the ghost of Catherine has claimed her lover who earlier has begged her to
come.