Well, it’s really about Galileo. The daughter thing is a hook, and I found that to be the weakest part of the book. Galileo, in this historical memoir, has had three children by a woman not his wife. The daughters are thus unmarriageable, and are sent to a convent. The daughter of the title sends him letters, usually including requests for money. This book provides considerable detail about the travails the great scientist endured in his quest to explain the world. The Catholic Church is the pre-eminent political institution of its time, and thus, Galileo must deal with the reality he inhabits, trying to find ways around the silliness of revealed truth. It is entertaining and interesting. Not a must read, and feel free to skip the letters from his daughter, but a worthwhile read nonetheless.