__The Calculus of Friendship.__In his book Strogatz writes about the letters that he sends back and forth with his high school calculus teacher, Mr. Joffary. The book contains over 30 years of correspondence, however the interesting twist is that the letters are not personal in nature, they are about mathematics. Strogatz, after high school and college, goes on to teach at MIT and also Cambridge, and during this time Mr. Joffary sends Steven math problems that his students present him. Strogatz then in turn sends Mr. Joffary proofs to the questions he asks and poses new questions for his students. Throughout their years of correspondence they touch topics such as infinity and limits, chaos, bifurcation, Hero's Formula, and relativity. The book contains a mixture of letters, proofs, and explanations about the topics discussed, and as each page turns the reader is able to see the relationship between teacher and student blossom.

Now I won't lie, a lot of the proofs presented in this book were beyond my level on mathematics, but the reason I kept turning the page was for the friendship that was growing between Steven and Mr. Joffary (or Joff as he would later call him). Both Steven and Joff go through a lot of ups and downs in life, however these are never present in the letters, only math. I got the feeling though that both Steven and Mr. Joffary knew that they had a lifelong friend, even if they never discussed it.

I think that the reason that I loved this book so much is because Mr. Joffary reminded me of my grandfather. My grandfather, Brian, taught math at Muskegon Community College for over 30 years and he is just as kind, thoughtful, and smart as Mr. Joffary. Even the jokes that Mr. Joffary includes in his letters, and his mannerisms reminded me of my grandfather and I couldn't help but smile. This was a book that not only makes you think, but also warms your heart. It is about the bond that is formed between a teacher and a student. and how sometimes the student becomes the teacher. If you are looking for a story about friendship and integrals, I suggest you pick up a copy of

__The Calculus of Friendship.__I will leave you with my favorite quote from the book, and a video of Steven Strogatz talking about his friendship and his letters to Mr. Joffary, you can clearly see how much this relationship meant to him.

*"This was a different kind of infinity than Joff had ever encountered before, a higher order of infinity. While I explained it to him, the sun began to set. We sat together on the beach and solved the problem, surrounded by the waves in Long Island Sound."*