The goal of this book is help you make your code better. And when we say "code", we literally mean the lines of code you are staring at in your editor. We’re not talking about the overall architecture of your project, or your choice of design patterns. Those are certainly important, but in our experience most of our day-to-day lives as programmers are spent on the “basic” stuff, like naming variables, writing loops, and attacking problems down at the function level. And a big part of this is reading and editing the code that’s already there.
KEY IDEA 1 - Code should be easy to understand.
KEY IDEA 2 - Code should be written to minimize the time it would take for someone else (may be you sixth months later) to understand it.
Is smaller always better?
The less code you write to solve a problem, the better. It probably takes less time to understand a 2000 line class than a 5000 line class