Descartes: The Life and times of a Genius (original 2005; edition 2006)

I would also have added a word of advice concerning the way to read this book, which is I would like it first to be read rapidly in its entirety, like a novel, without the reader forcing his attention too much or stopping at the difficulties which he may encounter in it, simply to have a broad view of the matters I have treated in it. And after that, if the reader judges that these matters merit examination, and is curious to know their causes, he can read the book a second time, in order to notice the sequence of my reasonings.

Descartes, "Letter from the Author,"
The Principles of Philosophy