The Conclusion
The conclusion is Mitch's time to give a little perspective on writing the book, as well as the whole experience of knowing Morrie. Remember how Morrie calls this book their "final thesis" (27.9)? Well, in academia theses get defended, so this is kind of Mitch's little spiel where he does just that.
Mitch shares with us how his life changed after knowing Morrie. For example, he actually calls his long-lost brother in Spain (in case you didn't notice, he dedicates the book to his brother as well, which is really saying something). He also tells us that the whole idea of writing his experience down was Morrie's idea. Because of course it was.
He ends the chapter by addressing us, his readers. He asks us if we've ever had anybody like Morrie in our lives and tells us just how amazing the experience can be. He recaps what he says on page one pretty much verbatim, and tells us "the teaching goes on" (27.17). And indeed it does. Not only does Morrie's teaching live on through this book, but Mitch has even become a bit of a teacher himself in writing this book for others to read and learn from.
Well done, Mitch. We're positive Morrie would be proud.
The Afterword
So here's the thing: Mitch actually wrote an afterword to Tuesdays with Morrie ten years after the book was first published. He comes back to us, the readers, after he's had years to process his experience.
He shares a statement that Morrie made about his belief in an afterlife, something Mitch stumbled across after he had written the book. Morrie said that he found life to be "too harmonious, grand, and overwhelming a universe to believe it's all an accident" (28.21). Wow. This is quite different from the generally agnostic take on things Morrie usually presents in the book.
Mitch tells us that what he misses about Morrie is just being around him. Old notes, tape recordings, and memories can't replace the feeling of being around his friend's smile and laugh. And Mitch also expresses his gratitude to all of us who have been inspired by his book. He admits that his years of watching the book become so popular have all been part of the journey that began when he called Morrie on that very first Tuesday.