The chapbooks have different series. There are folk stories & fairytales (series “F”), literature of the 19th century (series “19-L”) and this book by the French early scientist and philosopher Descartes (1596-1650) is part of the 17th century science & technology series. This is the discourse in which Descartes came to his famous saying “cogito ergo sum”, “I think, therefor I am”. I am not too well read in philosophy, but I of course knew about Descartes and his famous line. It has always been quite clear to me what it meant, but reading this discourse, I truely can’t follow the man himself. Descartes starts with saying what he studied and learned. Then he goes on saying that he believes that everything you can reason (including ancient texts) about can’t be the thruth, but because one can reason, one excists. I miss something there. The second half of the book is filled with the notion that investigating should be done with the senses and then I’m totally lost. Not because I can’t follow, but the lenghty blabla that soon makes me drop out off by lack of interest. Nope, this very philosophical writing is not my thing. But for those who like this kind of literature better, here is an English translation of Descartes’ most famous text available for only $ 5,- in a nicely printed A5 booklet.