This short booklet mainly provides some tools to look at complex systems. Perhaps it is a good state of affairs (I can not judge that), but it remains very theoretical. What is also striking is that most of the instruments can only be used if they can be displayed in the form of mathematical or schematic models, and that also appears to be applicable to a limited number of complex systems. Holland suggests that in the future a global theory of complex systems is possible, but at the same time he indicates that many questions remain open. For my purpose, - the use of complexity thinking in the study of history -, this book did not offer many relevant things. ( )