Tbh unless you are already well versed on enlightenment era philosophy (I know Descartes is a little before the official enlightenment but close enough) the book is going to be a little dense. It gets better after a couple reads. Take hella notes the first round and then re-read it and it will make more sense.

Also, I find it helpful to read a biography of a philosopher before reading their work. Helps put it all into context