Nice book about what might cause language change... I thought. In fact it's not so much about language change per se, but about the effect of the "invisible hand", which leads the people to follow a trend that they themselves never actually planned. Keller seeminly likes to cite various authors, maybe to show how much he read, and also goes on in lengthy discussions about the phonemena that eventually lead to changes. Unfortunately, he almost entirely neglects citing examples from real life changes... maybe this book should rather bear the title "Gewohnheitswandel" or simply "The theory of the invisible hand". It was a nice read, though I expected much more of it...