Barbara Liskov

"Documentation should explain not just what, but why. The why lasts longer."

"Modularity is freedom. Freedom requires responsibility."

"The shortest path to a solution is often the longest to understand. Choose understanding."

"Code is read far more often than it is written. Optimize for readers."

"A good invariant protects you from your own mistakes."

"The principle of substitution is the principle of trust. Be trustworthy."

"Every line of code is a commitment to the future. Be committed."

"The best design is often the one you didn't think of until you stopped thinking."

"Elegance in design comes from understanding the problem deeply, not from clever tricks."

"An interface should be easy to use correctly and hard to use incorrectly. Aspire to this."

"Software is never finished; it is abandoned. Design with succession in mind."

"The beauty of abstraction is that it lets you think at the right level."

"The key to reliable software is to design systems that can be understood and maintained by different people over time."

"Good code is not just code that works, but code that communicates its intent to future readers."

"When you design a system, you're not just solving today's problem—you're enabling tomorrow's solutions."

"Abstraction is the art of hiding complexity while revealing essential truth."

"A well-designed interface is a contract between the present and the future."

"The measure of a system's design is not how it performs today, but how easily it adapts tomorrow."

"In programming, as in life, consistency builds trust and reliability."

"Inheritance should reflect genuine relationships, not convenience."

"Every design decision is a commitment to your users and your successors."

"The principle of substitutability is not just about code—it's about keeping promises."

"Subtyping creates obligations; use it with the care of making a commitment."

"What appears simple on the surface often conceals profound complexity beneath."

"Design patterns emerge not from doctrine, but from observing what works in practice."

"The gap between specification and implementation reveals the true challenges of the craft."

"To understand a system, you must understand not just what it does, but why it does it that way."

"Good design feels inevitable in hindsight, but requires tremendous thought in practice."

"The objects in your system should have clear responsibilities, like people in a community."

"Interfaces are conversations between the designer's intent and the user's needs."