Hans Blum is a German author from the 16th century. He was a building theorist who studied Vitruvius, among other things. For this he also made a stay in Rome, where he was closest to this subject. After that he lived in Switzerland, where he produced his only known work of the 5 columns. I think Hans Blum admired Roman architecture very much and wanted to convey the form and use of the columns to other people. He also felt it was an opportunity for art.
The title already describes very well what it is about. It is about the 5 types of columns. It describes how the basics of the composition of the columns works. In addition, the book says how the columns can be useful for any architect and that a kind of art is expressed with it.
The book works in such a way that the 5 columns in the course are led through different topics. The topics are like chapters and the columns are listed again and again in the chapters, where they are compared with each other and show the differences. At the end of the book, examples of buildings are shown where the different columns are built in.
You can understand the book only with the pictures up to many points and see where the columns are different. So it has a lot of illustrations in the book. For the topic of the columns this is also very useful, because you can imagine the columns so exactly.
The book is not very thick, nor is it particularly large or small. It is also a very specific topic, which is written and drawn compactly.