This was such a comfortable read for me and touched me at many different levels.
Firstly, it is a very engaging story, involving just a small number of equally engaging characters. The two main characters are in the title, but they are brought together by their strong feelings for the third character in the book, the housekeeper's son, Root.
Of course, as explained in the blurb, that is just the Professor's nickname for the ten-year-old boy, and the name refers to the shape of his profile and its resemblence to the [square] root sign.
Then there is the mathematical threaad of the whole story. The professor relates everything in the world to numbers and mathematics. His enthusiasm for these connections is soon shared by the housekeeper and her son.
This approach to life so reminds me of my own childhood that I became excited and emotional as I read. You see, my own father, also a professor, took exactly the same approach with me. Consequently, I LOVE number theory, mathematics, geometry, trigonametry, algebra, fractals, calculus, trees, rivers, planets, gravity, colours, music, and on and on and on!
If you read this book, you may be stirred up in the same way, even if you have never been so stirred up in your past.
And you will want to share your discoveries with others.
Then there is the human relationships aspect of the book. I won't go any further on this one for fear of the risk of spoiling it for you.
Two other threads which captivated me in this little story were those of Japaness culture and the sport of baseball. A sub theme of the latter, which links nicely back to the human relationships in this book, is the collecting of player cards which many of us must have done, for whichever sport appealed to us, when we were children.
Finally, I would like to mention the theme surrounding memory loss, and the way in which we deal with that in our own lives and those closest to us. The author depicts this so well that I will not even attempt to describe those thoughts here.
This is a relatively short book, and I would classify it as a "must read." Highly recommended!