The object of this book is to meet and combat false conceptions, to co-ordinate true notions, and so to furnish the reader with some general information on the old and the new scholasticism. The advantage of the book is its two-sided perspective that contains historical investigations about the ancient sources of the scholastic philosophy and the decline from it. But it contains also a systematic perspective by which the doctrines of the scholastic philosophising are collected systematically. Therefore this book is an scholarly introduction into the scholastic philosophy dedicated for undergraduates.