Discuss the significance of the conversation between Lenina and Henry prompted by the Slough Crematorium in Brave New World.

The major significance of this conversation is that it
shows us how important the castes and conditioning are in maintaining stability in the
society.

As Henry and Lenina talk, she talks about how
happy she is that she is not an Epsilon.  But Henry points out to her how the
conditioning that people receive makes them all happy to be in the caste that they are
in.  He also points out that the people's different heredities make them want different
things.

These are very important points in this book.  A
major point of the book is that the World State has (or at least has tried to)
engineered things so that no one is discontented.  Through genetics and conditioning,
they have made people who are perfectly fitted for the jobs they will do and who are
happy with their status.

This is the best and worst thing
about the World State.  It is perfectly stable because everyone is happy (as Henry says)
but it is also terrible because everyone is denied the chance to be a human being. 
Instead, they are sort of robots who have been engineered to think and act in given
ways.  Because the conversation points this out to us, it is very
significant.