What is the significant relationship between the two characters in Tuesdays with Morrie?

The two characters with the significant relationship in
this book are Mitch (the author) and Morrie Schwartz, his college professor who he once
promised he'd keep in touch with.

As it turned out, Mitch
grew up and never did reconnect with the man who, in college, taught him several
life-lessons about relationships and keys to a happy and succesful life.  Then one
night, Mitch sees Morrie on a TV interview with Ted Koppel.  He is dying from ALS.  This
sparks Mitch's desire to go see his old professor, which turns into a series of visits,
all on Tuesdays, and later, what Mitch turns into this book--a record of his "last
class" with Morrie.

The main significance of the
relationship is unique to Mitch but not to Morrie.  Morrie is a man who makes deep and
personal conenctions with those around him.  Mitch, on the other hand, has been living a
very lonely and independent success-driven life.  Morrie teaches him how to reconnect
with himself and others and through his genuinely positive attitude, he shows Mitch how
to appreciate life for what it is.  Ironically, the lessons taught are heightened by the
fact that Morrie is dying, but certainly this is a man who would otherwise be just as
effective in encouraging people (like Mitch) to do more and be more, simply by taking
more time for friends, family, and appreciation of little
things.