Symmetries and Logical Visibility One More Time

My aim in this book was to explain the concept of mathematical structure and to show examples of techniques that are used to study them. It would be hard to do it honestly without introducing some elements of logic and set theory. In a textbook, the line of thought may sometimes get lost in technical details. Now, when all necessary material has been covered, I can give a summary and a brief description of what this book is about.