Book excerpt: Economists present their arguments in three different types of arguments: verbal, graphical, and mathematical. If you flip over introductory economic textbooks, you will notice that analysis is usually done based on verbal argument and diagrams. Even for intermediate and advanced textbooks, you will notice that the difference is the mathematical argument -- diagrams are still useful. This is also true for academic research. However, drawing a nice diagram is not easy. Standard software is not good for drawing economic diagrams. Either it is too simple or it is too professional. One nice drawing software is the TikZ package in LaTeX . However, it is a drawing programming so that there is a steep learning curve. This is the reason that I write this book.