There are two types of book.
- knowledge: A book which by reading it, gives you some pleasure or information
- growth: A book which by reading it, enables you to understand many other books
With the first, your knowledge grows linearly. With the second, it grows exponentionally.
Examples of growth books are those which give you new mental models (black swan, stubborn attachments, origins of political order), and original texts that many other books refrenece (plato’s republic, on liberty, weatlh of nations)