What does Quentin mean with the response "temporary" in the last part of his section?

There are several approaches that can be taken with this
particular idea.  It's a challenge to parse the meaning of the work through the use of
one word and it should be noted that the use of language should be seen in the larger
context and not attempted to make sense outside of it.  The idea of "temporary" might be
something we can use to see Quentin.  If we examine the use of the term in light of the
Compson family and Quentin himself, there can be much in way of appropriate use of the
term.  The exterior of success, being the eldest, being at Harvard, and being the one
that might "have it together," is a temporary facade.  Additionally, the notion of pain
might be something where temporal conditions apply.  On one hand, Quentin has trouble
reconciling whether or not his incestuous feelings for Caddy are temporary.  If they
are, then they might not seem valid expressions, and if they are not, then they come
into direct conflict with social expectations.  The more valid they are and thereby less
temporary, the worse the impact.  In regards to the pain experienced about the family's
dishonor with Caddy's "fall from grace" as well as the notion of honorable ideals
changing in a new setting of modernity (thereby being "temporary"), Quentin experiences
this in the present.  Yet, similar to his feelings about Caddy, if these are
"temporary," then the experience of pain is not valid.  At the same time, if the pain is
not "temporary," then its inescapable nature is excruciating to bear.   Perhaps, these
ideas are the reason for the use and repetition of the term.  Additionally, the idea of
time and its use in terms of the style of the writing in the novel might be a part of
this.  There is much which seems to be both temporary and permanent.  Benjy's conception
of time is one where events are posited in what makes sense to him, but lies outside the
full grasp of others.  With Quentin and his watch that he sets to perfect time before he
commits suicide, the notion of what is temporary and permanent becomes blurred in his
own mind.