Protocol for reading a mathematics book

In the introduction to " An introduction to Combinatorics by Alan Slomson " I found a good explanation of the protocol for reading a math book.

Once upon a time there was a programme on the radio for young children called Listen with Mother. (In those days it was assumed that it would be the mother who would be at home with the children.) In the first programme in 1950 the storyteller, Julia Lang, introduced the story she was about to tell by saying 'Are you sitting comfortably? Then we'll begin'. Apparently this introduction was not planned, but it caught on, and was used regularly until the programme ceased in 1982. When it comes to reading mathematics, however, this is not an appropriate beginning. A mathematics book cannot be read like a novel, sitting in a comfortable chair, with a glass by your side. Mathematics books need to be worked at. You need to be sitting at a table or a desk, with pencil and paper, both to work through the theory and to tackle the problems. A good guide is the amount of time it takes you to read the book. A novel can be read at a rate of about 60 pages an hour, whereas when it comes to many mathematics books you are doing well if you can read five pages an hour. (It follows that, even at 12 times the price, a mathematics book is good value for money!)

I would like to add that a good mathematics book can be read over and over. Some math books are companions for life.