Relationships
Relationships are a big theme in the book. The relationship (past and present) between Morrie and Mitch, between Morrie and his caregivers, between Morrie and his family, and between Mitch and his brother all play a big part in the story.
Attitude
Throughout his illness, Morrie displays a very positive mental attitude. He does not feel sorry for himself because his body is slowly deteriorating. He looks at the positives in his life and the things he is still able to do. His positive attitude inspires Mitch and others in the story.
Purpose
As he reflects back on his life, Morrie realizes he purpose was to educate and he does it until the day he dies. This pushes Mitch to realize he is fulfilling his purpose in life (journalism) and the purpose of re-connecting with his brother.
Dependency
Morrie learns that he needs to depend on others as his body fails him. Mitch grows to depend on Morrie as well for life lessons.
Regret
Mitch states that he has regrets in his life, such as not reaching out to Morrie sooner or losing touch with his brother. Morrie almost seems to believe that there are no regrets, and that everything happens for a reason.
Devotion
Once they make the pact, Mitch doesn't miss a Tuesday with Morrie. He meets with him week after week, religiously. This teaches Mitch the importance of holding true to your word. Morrie depended on Mitch to make this visit every week, and in the end, Mitch depended on Morrie to be there to teach him.
Love/Compassion
Throughout the book, we see the love between Morrie and Mitch, the compassion between Morrie and his wife, the compassion between Morrie and his team of nurses, and the compassion as Mitch worries about his brother. There is even compassion between Morrie and Ted Koppel as the two become friends.
Mentors
Morrie was a mentor to Mitch in college and again later in life. The reader realizes the importance of having someone to look up to and guide them through life. Morrie was able to teach Mitch lessons up until his death.
Aging
Morrie teaches Mitch and the reader that there is nothing to fear with aging, and that it is all a part of life. He says everything comes in steps and you just have to face each step as a new challenge or opportunity.