Here are the first few paragraphs from the preface.
As Ayn Rand has indicated, this book demonstrates how German philosophy led to Hitler and the Holocaust.
The Cause of Hitler’s Germanyis about two-thirds of The Ominous Parallels, a book of mine published in 1982 by Stein and Day. In the book, I intended a warning: If Americans continue to accept and act on the same philosophic ideas that led to the Third Reich, then America will have to follow a parallel course and suffer the same result.
The book, accordingly, studied American culture and history in as much detail as that given to Germany. Given our cultural state, however, I did not expect any such warning to be heeded or even heard, and it wasn’t. There is no improvement in the 30 years since, no change in the basic ideas ruling the United States (and the West as a whole). The Soviet Empire has collapsed, but the ideas of irrationalism, self-sacrifice, and collectivism still dominate and fuel murderous tyrannies, primarily now in the upsurging Middle East, but elsewhere, too.
Unlike The Ominous Parallels, this substantial portion of it is offered not primarily as a warning but rather as an explanation.