Barbara Liskov

"The substitution principle teaches us that good design respects our understanding of relationships."

"Complexity is not bad; unmanaged complexity is."

"The most powerful abstractions are those that reflect how people think about the world."

"In the long run, readability is performance—when people can understand code quickly, they can maintain and improve it quickly."

"A good programmer leaves a codebase better than they found it."

"The interface is the contract; honor it."

"Every language has its own way of expressing certain ideas; wisdom is choosing the right tool for your thought."

"The goal of abstraction is not perfection but pragmatism."

"When you design a system, you are encoding beliefs about the future; make sure they are good beliefs."

"A variable name is not a luxury; it is a form of communication."

"The beauty of a well-designed system is that it makes the complex seem simple."

"Inheritance is powerful, but composition is often simpler."

"The most important part of any system is its boundaries."

"To truly understand a system, you must first understand its constraints."

"Programming is about finding the right level of abstraction for the problem at hand."

"A good design anticipates growth without encouraging bloat."

"The conversation about how to solve the problem is often more important than the solution itself."

"Every line of code has a cost; make sure you understand what you are buying."